Util.js

/** * @fileoverview This is a utility class containing utility methods used on the * server and client. * @author alvin.lin.dev@gmail.com (Alvin Lin) */ /** * Empty constructor for the Util class, all functions will be static. */ function Util() { throw new Error('Util should not be instantiated!'); } /** * This method returns the sign of a number. * @param {number} x The number to check. * @return {number} */ Util.getSign = function(x) { if (x > 0) { return 1; } else if (x < 0) { return -1; } return 0; }; /** * Generates and returns a UID. * @param {?number=} length An optional length parameter for the UID to * to generate. If the length is not provided, this function will return a * UID of length 32. * @return {string} */ Util.generateUID = function(length) { if (!length) { length = 32; } var choice = 'abcdefghijklmnopqrstuvwxyz' + 'ABCDEFGHIJKLMNOPQRSTUVWXYZ' + '1234567890'; var uid = ''; for (var i = 0; i < length; ++i) { uid += choice.charAt(Math.floor(Math.random() * choice.length)); } return uid; }; /** * This method linearly scales a number from one range to another. * @param {number} x The number to scale. * @param {number} a1 The lower bound of the range to scale from. * @param {number} a2 The upper bound of the range to scale from. * @param {number} b1 The lower bound of the range to scale to. * @param {number} b2 The upper bound of the range to scale to. * @return {number} */ Util.linearScale = function(x, a1, a2, b1, b2) { return ((x - a1) * (b2 - b1) / (a2 - a1)) + b1; }; /** * Returns the Manhattan Distance between two points given their x and y * coordinates. * @param {number} x1 The x-coordinate of the first point. * @param {number} y1 The y-coordinate of the first point. * @param {number} x2 The x-coordinate of the second point. * @param {number} y2 The y-coordinate of the second point. * @return {number} */ Util.getManhattanDistance = function(x1, y1, x2, y2) { return Math.abs(x1 - x2) + Math.abs(y1 - y2); }; /** * Returns the squared Euclidean distance between two points given their * x and y coordinates. * @param {number} x1 The x-coordinate of the first point. * @param {number} y1 The y-coordinate of the first point. * @param {number} x2 The x-coordinate of the second point. * @param {number} y2 The y-coordinate of the second point. * @return {number} */ Util.getEuclideanDistance2 = function(x1, y1, x2, y2) { return ((x1 - x2) * (x1 - x2)) + ((y1 - y2) * (y1 - y2)); }; /** * Returns the true Euclidean distance between two points given their * x and y coordinates. * @param {number} x1 The x-coordinate of the first point. * @param {number} y1 The y-coordinate of the first point. * @param {number} x2 The x-coordinate of the second point. * @param {number} y2 The y-coordinate of the second point. * @return {number} */ Util.getEuclideanDistance = function(x1, y1, x2, y2) { return Math.sqrt(Util.getEuclideanDistance2(x1, y1, x2, y2)); }; /** * Given a value, a minimum, and a maximum, returns true if value is * between the minimum and maximum, inclusive of both bounds. This * functio will still work if min and max are switched. * @param {number} val The value to check. * @param {number} min The minimum bound. * @param {number} max The maximum bound. * @return {boolean} */ Util.inBound = function(val, min, max) { if (min > max) { return val >= max && val <= min; } return val >= min && val <= max; }; /** * Bounds a number to the given minimum and maximum, inclusive of both * bounds. This function will still work if min and max are switched. * @param {number} val The value to check. * @param {number} min The minimum number to bound to. * @param {number} max The maximum number to bound to. * @return {number} */ Util.bound = function(val, min, max) { if (min > max) { return Math.min(Math.max(val, max), min); } return Math.min(Math.max(val, min), max); }; /** * Returns a random floating-point number between the given min and max * values, exclusive of the max value. * @param {number} min The minimum number to generate. * @param {number} max The maximum number to generate. * @return {number} */ Util.randRange = function(min, max) { if (min >= max) { var swap = min; min = max; max = swap; } return (Math.random() * (max - min)) + min; }; /** * Returns a random integer between the given min and max values, exclusive * of the max value. * @param {number} min The minimum number to generate. * @param {number} max The maximum number to generate. * @return {number} */ Util.randRangeInt = function(min, max) { if (min >= max) { var swap = min; min = max; max = swap; } return Math.floor(Math.random() * (max - min)) + min; }; /** * Returns a random element in a given array. * @param {Array.<*>} array The array from which to select a random * element from. * @return {*} */ Util.choiceArray = function(array) { return array[Util.randRangeInt(0, array.length)]; }; if (typeof module === 'object') { module.exports = Util; } else { window.Constants = Util; }