/**
* Various utilities.
*
* @authors Alain Pitiot, Sotiri Bakagiannis, Thomas Pronk
* @version 2021.2.0
* @copyright (c) 2017-2020 Ilixa Ltd. (http://ilixa.com) (c) 2020-2021 Open Science Tools Ltd. (https://opensciencetools.org)
* @license Distributed under the terms of the MIT License
*/
import * as PIXI from 'pixi.js-legacy';
/**
* Syntactic sugar for Mixins
*
* <p>This is heavily adapted from: http://justinfagnani.com/2015/12/21/real-mixins-with-javascript-classes/</p>
*
* @name module:util.MixinBuilder
* @class
* @param {Object} superclass
*
* @example
* class BaseClass { ... }
* let Mixin1 = (superclass) => class extends superclass { ... }
* let Mixin2 = (superclass) => class extends superclass { ... }
* class NewClass extends mix(BaseClass).with(Mixin1, Mixin2) { ... }
*/
export let mix = (superclass) => new MixinBuilder(superclass);
class MixinBuilder
{
constructor(superclass)
{
this.superclass = superclass;
}
/**
*
* @param mixins
* @returns {*}
*/
with(...mixins)
{
return mixins.reduce((c, mixin) => mixin(c), this.superclass);
}
}
/**
* Convert the resulting value of a promise into a tupple.
*
* @name module:util.promiseToTupple
* @function
* @public
* @param {Promise} promise - the promise
* @return {Object[]} the resulting value in the format [error, return data]
* where error is null if there was no error
*/
export function promiseToTupple(promise)
{
return promise
.then(data => [null, data])
.catch(error => [error, null]);
}
/**
* Get a Universally Unique Identifier (RFC4122 version 4)
* <p> See details here: https://www.ietf.org/rfc/rfc4122.txt</p>
*
* @name module:util.makeUuid
* @function
* @public
* @return {string} the uuid
*/
export function makeUuid()
{
return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function (c)
{
const r = Math.random() * 16 | 0, v = (c === 'x') ? r : (r & 0x3 | 0x8);
return v.toString(16);
});
}
/**
* Get the error stack of the calling, exception-throwing function.
*
* @name module:util.getErrorStack
* @function
* @public
* @return {string} the error stack as a string
*/
export function getErrorStack()
{
try
{
throw Error('');
}
catch (error)
{
// we need to remove the second line since it references getErrorStack:
let stack = error.stack.split("\n");
stack.splice(1, 1);
return JSON.stringify(stack.join('\n'));
}
}
/**
* Test if x is an 'empty' value.
*
* @name module:util.isEmpty
* @function
* @public
* @param {Object} x the value to test
* @return {boolean} true if x is one of the following: undefined, [], [undefined]
*/
export function isEmpty(x)
{
if (typeof x === 'undefined')
{
return true;
}
if (!Array.isArray(x))
{
return false;
}
if (x.length === 0)
{
return true;
}
if (x.length === 1 && typeof x[0] === 'undefined')
{
return true;
}
return false;
}
/**
* Detect the user's browser.
*
* <p> Note: since user agent is easily spoofed, we use a more sophisticated approach, as described here:
* https://stackoverflow.com/a/9851769</p>
*
* @name module:util.detectBrowser
* @function
* @public
* @return {string} the detected browser, one of 'Opera', 'Firefox', 'Safari',
* 'IE', 'Edge', 'EdgeChromium', 'Chrome', 'unknown'
*/
export function detectBrowser()
{
// Opera 8.0+
const isOpera = (!!window.opr && !!opr.addons) || !!window.opera || navigator.userAgent.indexOf(' OPR/') >= 0;
if (isOpera)
{
return 'Opera';
}
// Firefox 1.0+
const isFirefox = (typeof InstallTrigger !== 'undefined');
if (isFirefox)
{
return 'Firefox';
}
// Safari 3.0+ "[object HTMLElementConstructor]"
const isSafari = /constructor/i.test(window.HTMLElement) || (function (p)
{
return p.toString() === "[object SafariRemoteNotification]";
})(!window['safari'] || (typeof safari !== 'undefined' && safari.pushNotification));
if (isSafari)
{
return 'Safari';
}
// Internet Explorer 6-11
// const isIE6 = !window.XMLHttpRequest;
// const isIE7 = document.all && window.XMLHttpRequest && !XDomainRequest && !window.opera;
// const isIE8 = document.documentMode==8;
const isIE = /*@cc_on!@*/false || !!document.documentMode;
if (isIE)
{
return 'IE';
}
// Edge 20+
const isEdge = !isIE && !!window.StyleMedia;
if (isEdge)
{
return 'Edge';
}
// Chrome 1+
const isChrome = window.chrome;
if (isChrome)
{
return 'Chrome';
}
// Chromium-based Edge:
const isEdgeChromium = isChrome && (navigator.userAgent.indexOf("Edg") !== -1);
if (isEdgeChromium)
{
return 'EdgeChromium';
}
// Blink engine detection
const isBlink = (isChrome || isOpera) && !!window.CSS;
if (isBlink)
{
return 'Blink';
}
return 'unknown';
}
/**
* Convert obj to its numerical form.
*
* <ul>
* <li>number -> number, e.g. 2 -> 2</li>
* <li>[number] -> [number], e.g. [1,2,3] -> [1,2,3]</li>
* <li>numeral string -> number, e.g. "8" -> 8</li>
* <li>[number | numeral string] -> [number], e.g. [1, 2, "3"] -> [1,2,3]</li>
* </ul>
*
* @name module:util.toNumerical
* @function
* @public
* @param {Object} obj - the input object
* @return {number | number[]} the numerical form of the input object
*/
export function toNumerical(obj)
{
const response = {
origin: 'util.toNumerical',
context: 'when converting an object to its numerical form'
};
try
{
if (obj === null)
{
throw 'unable to convert null to a number';
}
if (typeof obj === 'undefined')
{
throw 'unable to convert undefined to a number';
}
if (typeof obj === 'number')
{
return obj;
}
const convertToNumber = (input) =>
{
const n = Number.parseFloat(input);
if (Number.isNaN(n))
{
throw `unable to convert ${input} to a number`;
}
return n;
};
if (Array.isArray(obj))
{
return obj.map(convertToNumber);
}
const arrayMaybe = turnSquareBracketsIntoArrays(obj);
if (Array.isArray(arrayMaybe))
{
return arrayMaybe.map(convertToNumber);
}
if (typeof obj === 'string')
{
return convertToNumber(obj);
}
throw 'unable to convert the object to a number';
}
catch (error)
{
throw Object.assign(response, { error });
}
}
/**
* Check whether a point lies within a polygon
* <p>We are using the algorithm described here: https://wrf.ecse.rpi.edu//Research/Short_Notes/pnpoly.html</p>
*
* @name module:util.IsPointInsidePolygon
* @function
* @public
* @param {number[]} point - the point
* @param {Object} vertices - the vertices defining the polygon
* @return {boolean} whether or not the point lies within the polygon
*/
export function IsPointInsidePolygon(point, vertices)
{
const x = point[0];
const y = point[1];
let isInside = false;
for (let i = 0, j = vertices.length - 1; i < vertices.length; j = i++)
{
const xi = vertices[i][0], yi = vertices[i][1];
const xj = vertices[j][0], yj = vertices[j][1];
const intersect = ((yi > y) !== (yj > y)) && (x < (xj - xi) * (y - yi) / (yj - yi) + xi);
if (intersect)
{
isInside = !isInside;
}
}
return isInside;
}
/**
* Shuffle an array in place using the Fisher-Yastes's modern algorithm
* <p>See details here: https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle#The_modern_algorithm</p>
*
* @name module:util.shuffle
* @function
* @public
* @param {Object[]} array - the input 1-D array
* @return {Object[]} the shuffled array
*/
export function shuffle(array)
{
for (let i = array.length - 1; i > 0; i--)
{
const j = Math.floor(Math.random() * (i + 1));
[array[i], array[j]] = [array[j], array[i]];
}
return array;
}
/**
* Get the position of the object, in pixel units
*
* @name module:util.getPositionFromObject
* @function
* @public
* @param {Object} object - the input object
* @param {string} units - the units
* @returns {number[]} the position of the object, in pixel units
*/
export function getPositionFromObject(object, units)
{
const response = {
origin: 'util.getPositionFromObject',
context: 'when getting the position of an object'
};
try
{
if (typeof object === 'undefined')
{
throw 'cannot get the position of an undefined object';
}
let objectWin = undefined;
// the object has a getPos function:
if (typeof object.getPos === 'function')
{
units = object.units;
objectWin = object.win;
object = object.getPos();
}
// convert object to pixel units:
return to_px(object, units, objectWin);
}
catch (error)
{
throw Object.assign(response, {error});
}
}
/**
* Convert the position to pixel units.
*
* @name module:util.to_px
* @function
* @public
* @param {number[]} pos - the input position
* @param {string} posUnit - the position units
* @param {Window} win - the associated Window
* @param {boolean} [integerCoordinates = false] - whether or not to round the position coordinates.
* @returns {number[]} the position in pixel units
*/
export function to_px(pos, posUnit, win, integerCoordinates = false)
{
const response = {
origin: 'util.to_px',
context: 'when converting a position to pixel units'
};
let pos_px;
if (posUnit === 'pix')
{
pos_px = pos;
}
else if (posUnit === 'norm')
{
pos_px = [pos[0] * win.size[0] / 2.0, pos[1] * win.size[1] / 2.0];
}
else if (posUnit === 'height')
{
const minSize = Math.min(win.size[0], win.size[1]);
pos_px = [pos[0] * minSize, pos[1] * minSize];
}
else
{
throw Object.assign(response, {error: `unknown position units: ${posUnit}`});
}
if (integerCoordinates)
{
return [Math.round(pos_px[0]), Math.round(pos_px[1])];
}
else
{
return pos_px;
}
}
/**
* Convert the position to norm units.
*
* @name module:util.to_norm
* @function
* @public
* @param {number[]} pos - the input position
* @param {string} posUnit - the position units
* @param {Window} win - the associated Window
* @returns {number[]} the position in norm units
*/
export function to_norm(pos, posUnit, win)
{
const response = {origin: 'util.to_norm', context: 'when converting a position to norm units'};
if (posUnit === 'norm')
{
return pos;
}
if (posUnit === 'pix')
{
return [pos[0] / (win.size[0] / 2.0), pos[1] / (win.size[1] / 2.0)];
}
if (posUnit === 'height')
{
const minSize = Math.min(win.size[0], win.size[1]);
return [pos[0] * minSize / (win.size[0] / 2.0), pos[1] * minSize / (win.size[1] / 2.0)];
}
throw Object.assign(response, {error: `unknown position units: ${posUnit}`});
}
/**
* Convert the position to height units.
*
* @name module:util.to_height
* @function
* @public
* @param {number[]} pos - the input position
* @param {string} posUnit - the position units
* @param {Window} win - the associated Window
* @returns {number[]} the position in height units
*/
export function to_height(pos, posUnit, win)
{
const response = {
origin: 'util.to_height',
context: 'when converting a position to height units'
};
if (posUnit === 'height')
{
return pos;
}
if (posUnit === 'pix')
{
const minSize = Math.min(win.size[0], win.size[1]);
return [pos[0] / minSize, pos[1] / minSize];
}
if (posUnit === 'norm')
{
const minSize = Math.min(win.size[0], win.size[1]);
return [pos[0] * win.size[0] / 2.0 / minSize, pos[1] * win.size[1] / 2.0 / minSize];
}
throw Object.assign(response, {error: `unknown position units: ${posUnit}`});
}
/**
* Convert the position to window units.
*
* @name module:util.to_win
* @function
* @public
* @param {number[]} pos - the input position
* @param {string} posUnit - the position units
* @param {Window} win - the associated Window
* @returns {number[]} the position in window units
*/
export function to_win(pos, posUnit, win)
{
const response = {origin: 'util.to_win', context: 'when converting a position to window units'};
try
{
if (win._units === 'pix')
{
return to_px(pos, posUnit, win);
}
if (win._units === 'norm')
{
return to_norm(pos, posUnit, win);
}
if (win._units === 'height')
{
return to_height(pos, posUnit, win);
}
throw `unknown window units: ${win._units}`;
}
catch (error)
{
throw Object.assign(response, {response, error});
}
}
/**
* Convert the position to given units.
*
* @name module:util.to_unit
* @function
* @public
* @param {number[]} pos - the input position
* @param {string} posUnit - the position units
* @param {Window} win - the associated Window
* @param {string} targetUnit - the target units
* @returns {number[]} the position in target units
*/
export function to_unit(pos, posUnit, win, targetUnit)
{
const response = {origin: 'util.to_unit', context: 'when converting a position to different units'};
try
{
if (targetUnit === 'pix')
{
return to_px(pos, posUnit, win);
}
if (targetUnit === 'norm')
{
return to_norm(pos, posUnit, win);
}
if (targetUnit === 'height')
{
return to_height(pos, posUnit, win);
}
throw `unknown target units: ${targetUnit}`;
}
catch (error)
{
throw Object.assign(response, {error});
}
}
/**
* Convert a position to a PIXI Point.
*
* @name module:util.to_pixiPoint
* @function
* @public
* @param {number[]} pos - the input position
* @param {string} posUnit - the position units
* @param {Window} win - the associated Window
* @param {boolean} [integerCoordinates = false] - whether or not to round the PIXI Point coordinates.
* @returns {number[]} the position as a PIXI Point
*/
export function to_pixiPoint(pos, posUnit, win, integerCoordinates = false)
{
const pos_px = to_px(pos, posUnit, win);
if (integerCoordinates)
{
return new PIXI.Point(Math.round(pos_px[0]), Math.round(pos_px[1]));
}
else
{
return new PIXI.Point(pos_px[0], pos_px[1]);
}
}
/**
* Convert an object to its string representation, taking care of symbols.
*
* <p>Note: if the object is not already a string, we JSON stringify it and detect circularity.</p>
*
* @name module:util.toString
* @function
* @public
* @param {Object} object - the input object
* @return {string} a string representation of the object or 'Object (circular)'
*/
export function toString(object)
{
if (typeof object === 'undefined')
{
return 'undefined';
}
if (!object)
{
return 'null';
}
if (typeof object === 'string')
{
return object;
}
// if the object is a class and has a toString method:
if (object.constructor.toString().substring(0, 5) === 'class' && typeof object.toString === 'function')
{
return object.toString();
}
try
{
const symbolReplacer = (key, value) =>
{
if (typeof value === 'symbol')
{
value = Symbol.keyFor(value);
}
return value;
};
return JSON.stringify(object, symbolReplacer);
}
catch (e)
{
return 'Object (circular)';
}
}
if (!String.prototype.format)
{
String.prototype.format = function ()
{
var args = arguments;
return this
.replace(/{(\d+)}/g, function (match, number)
{
return typeof args[number] != 'undefined' ? args[number] : match;
})
.replace(/{([$_a-zA-Z][$_a-zA-Z0-9]*)}/g, function (match, name)
{
//console.log("n=" + name + " args[0][name]=" + args[0][name]);
return args.length > 0 && args[0][name] !== undefined ? args[0][name] : match;
});
};
}
/**
* Get the most informative error from the server response from a jquery server request.
*
* @name module:util.getRequestError
* @function
* @public
* @param jqXHR
* @param textStatus
* @param errorThrown
*/
export function getRequestError(jqXHR, textStatus, errorThrown)
{
let errorMsg = 'unknown error';
if (typeof jqXHR.responseJSON !== 'undefined')
{
errorMsg = jqXHR.responseJSON;
}
else if (typeof jqXHR.responseText !== 'undefined')
{
errorMsg = jqXHR.responseText;
}
else if (typeof errorThrown !== 'undefined')
{
errorMsg = errorThrown;
}
return errorMsg;
}
/**
* Test whether an object is either an integer or the string representation of an integer.
* <p>This is adapted from: https://stackoverflow.com/a/14794066</p>
*
* @name module:util.isInt
* @function
* @public
* @param {Object} obj - the input object
* @returns {boolean} whether or not the object is an integer or the string representation of an integer
*/
export function isInt(obj)
{
if (isNaN(obj))
{
return false;
}
const x = parseFloat(obj);
return (x | 0) === x;
}
/**
* Get the URL parameters.
*
* @name module:util.getUrlParameters
* @function
* @public
* @returns {URLSearchParams} the iterable URLSearchParams
*
* @example
* const urlParameters = util.getUrlParameters();
* for (const [key, value] of urlParameters)
* console.log(key + ' = ' + value);
*
*/
export function getUrlParameters()
{
const urlQuery = window.location.search.slice(1);
return new URLSearchParams(urlQuery);
/*let urlMap = new Map();
for (const entry of urlParameters)
urlMap.set(entry[0], entry[1])
return urlMap;*/
}
/**
* Add info extracted from the URL to the given dictionary.
*
* <p>We exclude all URL parameters starting with a double underscore
* since those are reserved for client/server communication</p>
*
* @name module:util.addInfoFromUrl
* @function
* @public
* @param {Object} info - the dictionary
*/
export function addInfoFromUrl(info)
{
const infoFromUrl = getUrlParameters();
// note: parameters starting with a double underscore are reserved for client/server communication,
// we do not add them to info
// for (const [key, value] of infoFromUrl)
infoFromUrl.forEach((value, key) =>
{
if (key.indexOf('__') !== 0)
{
info[key] = value;
}
});
return info;
}
/**
* Select values from an array.
*
* <p> 'selection' can be a single integer, an array of indices, or a string to be parsed, e.g.:
* <ul>
* <li>5</li>
* <li>[1,2,3,10]</li>
* <li>'1,5,10'</li>
* <li>'1:2:5'</li>
* <li>'5:'</li>
* <li>'-5:-2, 9, 11:5:22'</li>
* </ul></p>
*
* @name module:util.selectFromArray
* @function
* @public
* @param {Array.<Object>} array - the input array
* @param {number | Array.<number> | string} selection - the selection
* @returns {Object | Array.<Object>} the array of selected items
*/
export function selectFromArray(array, selection)
{
// if selection is an integer, or a string representing an integer, we treat it as an index in the array
// and return that entry:
if (isInt(selection))
{
return [array[parseInt(selection)]];
}// if selection is an array, we treat it as a list of indices
// and return an array with the entries corresponding to those indices:
else if (Array.isArray(selection))
{
// Pick out `array` items matching indices contained in `selection` in order
return selection.map(i => array[i]);
}// if selection is a string, we decode it:
else if (typeof selection === 'string')
{
if (selection.indexOf(',') > -1)
{
return selection.split(',').map(a => selectFromArray(array, a));
}// return flattenArray( selection.split(',').map(a => selectFromArray(array, a)) );
else if (selection.indexOf(':') > -1)
{
let sliceParams = selection.split(':').map(a => parseInt(a));
if (sliceParams.length === 3)
{
return sliceArray(array, sliceParams[0], sliceParams[2], sliceParams[1]);
}
else
{
return sliceArray(array, ...sliceParams);
}
}
}
else
{
throw {
origin: 'selectFromArray',
context: 'when selecting entries from an array',
error: 'unknown selection type: ' + (typeof selection)
};
}
}
/**
* Recursively flatten an array of arrays.
*
* @name module:util.flattenArray
* @function
* @public
* @param {Array.<Object>} array - the input array of arrays
* @returns {Array.<Object>} the flatten array
*/
export function flattenArray(array)
{
return array.reduce(
(flat, next) =>
{
flat.push((Array.isArray(next) && Array.isArray(next[0])) ? flattenArray(next) : next);
return flat;
},
[]
);
}
/**
* Slice an array.
*
* @name module:util.sliceArray
* @function
* @public
* @param {Array.<Object>} array - the input array
* @param {number} [from= NaN] - the start of the slice
* @param {number} [to= NaN] - the end of the slice
* @param {number} [step= NaN] - the step of the slice
* @returns {Array.<Object>} the array slice
*/
export function sliceArray(array, from = NaN, to = NaN, step = NaN)
{
if (isNaN(from))
{
from = 0;
}
if (isNaN(to))
{
to = array.length;
}
let arraySlice = array.slice(from, to);
if (isNaN(step))
{
return arraySlice;
}
if (step < 0)
{
arraySlice.reverse();
}
step = Math.abs(step);
if (step === 1)
{
return arraySlice;
}
else
{
return arraySlice.filter((e, i) => (i % step === 0));
}
}
/**
* Offer data as download in the browser.
*
* @name module:util.offerDataForDownload
* @function
* @public
* @param {string} filename - the name of the file to be downloaded
* @param {*} data - the data
* @param {string} type - the MIME type of the data, e.g. 'text/csv' or 'application/json'
*/
export function offerDataForDownload(filename, data, type)
{
const blob = new Blob([data], {type});
if (window.navigator.msSaveOrOpenBlob)
{
window.navigator.msSaveBlob(blob, filename);
}
else
{
const anchor = document.createElement('a');
anchor.href = window.URL.createObjectURL(blob);
anchor.download = filename;
document.body.appendChild(anchor);
anchor.click();
document.body.removeChild(anchor);
}
}
/**
* Convert a string representing a JSON array, e.g. "[1, 2]" into an array, e.g. ["1","2"].
* This approach overcomes the built-in JSON parsing limitations when it comes to eg. floats
* missing the naught prefix, and is able to process several arrays, e.g. "[1,2][3,4]".
*
* @name module:util.turnSquareBracketsIntoArrays
* @function
* @public
* @param {string} input - string potentially containing JSON arrays
* @param {string} max - how many matches to return, unwrap resulting array if less than two
* @returns {array} an array if arrays were found, undefined otherwise
*/
export function turnSquareBracketsIntoArrays(input, max = 1)
{
// Only interested in strings
// https://stackoverflow.com/questions/4059147
if (String(input) !== input)
{
return;
}
// Matches content within square brackets (using literal
// form is MDN's advice for patterns unlikely to change)
const matchesMaybe = input.match(/\[(.*?)\]/g);
// Exit if no array-like matches found
if (matchesMaybe === null)
{
return;
}
// Reformat content for each match
const matches = matchesMaybe.map((data) =>
{
return data
// Remove the square brackets
.replace(/[\[\]]+/g, '')
// Eat up space after comma
.split(/[, ]+/);
}
);
if (max < 2)
{
return matches[0];
}
return matches;
}
/**
* Generates random integers a-la NumPy's in the "half-open" interval [min, max). In other words, from min inclusive to max exclusive. When max is undefined, as is the case by default, results are chosen from [0, min). An error is thrown if max is less than min.
*
* @name module:util.randint
* @function
* @public
* @param {number} [min = 0] - lowest integer to be drawn, or highest plus one if max is undefined (default)
* @param {number} max - one above the largest integer to be drawn
* @returns {number} a random integer in the requested range (signed)
*/
export function randint(min = 0, max)
{
let lo = min;
let hi = max;
if (typeof max === 'undefined')
{
hi = lo;
lo = 0;
}
if (hi < lo)
{
throw {
origin: 'util.randint',
context: 'when generating a random integer',
error: 'min should be <= max'
};
}
return Math.floor(Math.random() * (hi - lo)) + lo;
}
/**
* Round to a certain number of decimal places.
*
* This is the Crib Sheet provided solution, but please note that as of 2020 the most popular SO answer is different.
*
* @name module:util.round
* @function
* @public
* @see {@link https://stackoverflow.com/questions/11832914|Stack Overflow}
* @param {number} input - the number to be rounded
* @param {number} places - the max number of decimals desired
* @returns {number} input rounded to the specified number of decimal places at most
*/
export function round(input, places = 0)
{
return +(Math.round(`${input}e+${places}`) + `e-${places}`);
}
/**
* Calculate the sum of the elements in the input array.
*
* If 'input' is not an array, then we return start.
*
* @name module:util.sum
* @function
* @public
* @param {array} input - an array of numbers, or of objects that can be cast into a number, e.g. ['1', 2.5, 3e1]
* @param {number} start - value added to the sum of numbers (a la Python)
* @returns {number} the sum of the elements in the array + start
*/
export function sum(input = [], start = 0)
{
if (!Array.isArray(input))
{
return start;
}
const add = (a, b) => a + b;
return input
// type cast everything as a number
.map(value => Number(value))
// drop non numeric looking entries (note: needs transpiling for IE11)
.filter(value => Number.isNaN(value) === false)
// add up each successive entry, starting with start
.reduce(add, start);
}
/**
* Calculate the average of the elements in the input array.
*
* If 'input' is not an array, or if it is an empty array, then we return 0.
*
* @name module:util.average
* @function
* @public
* @param {array} input - an array of numbers, or of objects that can be cast into a number, e.g. ['1', 2.5, 3e1]
* @returns {number} the average of the elements in the array
*/
export function average(input = [])
{
if (!Array.isArray(input))
{
return 0;
}
if (input.length === 0)
{
return 0;
}
return sum(input, 0) / input.length;
}
/**
* Sort the elements of the input array, in increasing alphabetical or numerical order.
*
* @name module:util.sort
* @function
* @public
* @param {array} input - an array of numbers or of strings
* @return {array} the sorted array
* @throws if 'input' is not an array, or if its elements are not consistent in types, or if they are not all either numbers or
* strings
*/
export function sort(input)
{
const response = {
origin: 'util.sort',
context: 'when sorting the elements of an array'
};
try
{
if (!Array.isArray(input))
{
throw 'the input argument should be an array';
}
// check the type and consistency of the array, and sort it accordingly:
const isNumberArray = input.every(element => typeof element === "number");
if (isNumberArray)
{
return input.sort((a, b) => (a - b));
}
const isStringArray = input.every(element => typeof element === "string");
if (isStringArray)
{
return input.sort();
}
throw 'the input array should either consist entirely of strings or of numbers';
}
catch (error)
{
throw {...response, error};
}
}
/**
* Create a sequence of integers.
*
* The sequence is such that the integer at index i is: start + step * i, with i >= 0 and start + step * i < stop
*
* <p> Note: this is a JavaScript implement of the Python range function, which explains the unusual management of arguments.</p>
*
* @name module:util.range
* @function
* @public
* @param {Number} [start=0] - the value of start
* @param {Number} stop - the value of stop
* @param {Number} [step=1] - the value of step
* @returns {Number[]} the range as an array of numbers
*/
export function range(...args)
{
const response = {
origin: 'util.range',
context: 'when building a range of numbers'
};
try
{
let start, stop, step;
switch (args.length)
{
case 0:
throw 'at least one argument is required';
// 1 arg: start = 0, stop = arg, step = 1
case 1:
start = 0;
stop = args[0];
step = 1;
break;
// 2 args: start = arg1, stop = arg2
case 2:
start = args[0];
stop = args[1];
step = 1;
break;
// 3 args:
case 3:
start = args[0];
stop = args[1];
step = args[2];
break;
default:
throw 'range requires at least one and at most 3 arguments'
}
if (!Number.isInteger(start)) {
throw 'start should be an integer';
}
if (!Number.isInteger(stop)) {
throw 'stop should be an integer';
}
if (!Number.isInteger(step)) {
throw 'step should be an integer';
}
// if start >= stop, the range is empty:
if (start >= stop)
{
return [];
}
let result = [];
for (let i = start; i < stop; i += step)
{
result.push(i);
}
return result;
}
catch (error)
{
throw {...response, error};
}
}
/**
* Create a boolean function that compares an input element to the given value.
*
* @name module:util._match
* @function
* @private
* @param {Number|string|object|null} value the matching value
* @return {} a function that compares an input element to the given value
*/
function _match(value)
{
const response = {
origin: 'util._match',
context: 'when creating a function that compares an input element to the given value'
};
try
{
// function:
if (typeof value === 'function')
{
throw 'the value cannot be a function';
}
// NaN:
if (Number.isNaN(value))
{
return (element) => Number.isNaN(element);
}
// null:
if (value === null)
{
return (element) => element === null;
}
// object: we compare using JSON.stringify
if (typeof value === 'object')
{
const jsonValue = JSON.stringify(value);
if (typeof jsonValue === 'undefined')
{
throw 'value could not be converted to a JSON string';
}
return (element) =>
{
const jsonElement = JSON.stringify(element);
return (jsonElement === jsonValue);
}
}
// everything else:
return (element) => element === value;
}
catch (error)
{
throw {...response, error};
}
}
/**
* Count the number of elements in the input array that match the given value.
*
* <p> Note: count is able to handle NaN, null, as well as any value convertible to a JSON string.</p>
*
* @name module:util.count
* @function
* @public
* @param {array} input the input array
* @param {Number|string|object|null} value the matching value
* @returns the number of matching elements
*/
export function count(input, value)
{
const response = {
origin: 'util.count',
context: 'when counting how many elements in the input array match the given value'
};
try
{
if (!Array.isArray(input))
{
throw 'the input argument should be an array';
}
const match = _match(value);
let nbMatches = 0;
input.forEach(element =>
{
if (match(element))
{
++ nbMatches;
}
});
return nbMatches;
}
catch (error)
{
throw {...response, error};
}
}
/**
* Get the index in the input array of the first element that matches the given value.
*
* <p> Note: index is able to handle NaN, null, as well as any value convertible to a JSON string.</p>
*
* @name module:util.index
* @function
* @public
* @param {array} input the input array
* @param {Number|string|object|null} value the matching value
* @returns the index of the first element that matches the value
* @throws if the input array does not contain any matching element
*/
export function index(input, value)
{
const response = {
origin: 'util.index',
context: 'when getting the index in the input array of the first element that matches the given value'
};
try
{
if (!Array.isArray(input))
{
throw 'the input argument should be an array';
}
const match = _match(value);
const index = input.findIndex(match);
if (index === -1)
{
throw 'no element in the input array matches the value';
}
return index;
}
catch (error)
{
throw {...response, error};
}
}
/**
* Return the file extension corresponding to an audio mime type.
* If the provided mimeType is not a string (e.g. null, undefined, an array)
* or unknown, then '.dat' is returned, instead of throwing an exception.
*
* @name module:util.extensionFromMimeType
* @function
* @public
* @param {string} mimeType the MIME type, e.g. 'audio/webm;codecs=opus'
* @return {string} the corresponding file extension, e.g. '.webm'
*/
export function extensionFromMimeType(mimeType)
{
if (typeof mimeType !== 'string')
{
return '.dat';
}
if (mimeType.indexOf('audio/webm') === 0)
{
return '.webm';
}
if (mimeType.indexOf('audio/ogg') === 0)
{
return '.ogg';
}
if (mimeType.indexOf('audio/wav') === 0)
{
return '.wav';
}
return '.dat';
}