Type checking examples in JavaScript. Code from AngularJS source. Also a few Array and Object helpers.
/**
* @ngdoc function
* @name angular.lowercase
* @function
*
* @description Converts the specified string to lowercase.
* @param {string} string String to be converted to lowercase.
* @returns {string} Lowercased string.
*/
var lowercase = function(string){return isString(string) ? string.toLowerCase() : string;};
var /** holds major version number for IE or NaN for real browsers */
msie = int((/msie (d+)/.exec(lowercase(navigator.userAgent)) || [])[1]),
jqLite, // delay binding since jQuery could be loaded after us.
jQuery, // delay binding
slice = [].slice,
push = [].push,
toString = Object.prototype.toString,
/** @name angular */
angular = window.angular || (window.angular = {})
;
/**
* @ngdoc function
* @name angular.isUndefined
* @function
*
* @description
* Determines if a reference is undefined.
*
* @param {*} value Reference to check.
* @returns {boolean} True if `value` is undefined.
*/
function isUndefined(value){return typeof value == 'undefined';}
/**
* @ngdoc function
* @name angular.isDefined
* @function
*
* @description
* Determines if a reference is defined.
*
* @param {*} value Reference to check.
* @returns {boolean} True if `value` is defined.
*/
function isDefined(value){return typeof value != 'undefined';}
/**
* @ngdoc function
* @name angular.isObject
* @function
*
* @description
* Determines if a reference is an `Object`. Unlike `typeof` in JavaScript, `null`s are not
* considered to be objects.
*
* @param {*} value Reference to check.
* @returns {boolean} True if `value` is an `Object` but not `null`.
*/
function isObject(value){return value != null && typeof value == 'object';}
/**
* @ngdoc function
* @name angular.isString
* @function
*
* @description
* Determines if a reference is a `String`.
*
* @param {*} value Reference to check.
* @returns {boolean} True if `value` is a `String`.
*/
function isString(value){return typeof value == 'string';}
/**
* @ngdoc function
* @name angular.isNumber
* @function
*
* @description
* Determines if a reference is a `Number`.
*
* @param {*} value Reference to check.
* @returns {boolean} True if `value` is a `Number`.
*/
function isNumber(value){return typeof value == 'number';}
/**
* @ngdoc function
* @name angular.isDate
* @function
*
* @description
* Determines if a value is a date.
*
* @param {*} value Reference to check.
* @returns {boolean} True if `value` is a `Date`.
*/
function isDate(value){
return toString.apply(value) == '[object Date]';
}
/**
* @ngdoc function
* @name angular.isArray
* @function
*
* @description
* Determines if a reference is an `Array`.
*
* @param {*} value Reference to check.
* @returns {boolean} True if `value` is an `Array`.
*/
function isArray(value) {
return toString.apply(value) == '[object Array]';
}
/**
* @ngdoc function
* @name angular.isFunction
* @function
*
* @description
* Determines if a reference is a `Function`.
*
* @param {*} value Reference to check.
* @returns {boolean} True if `value` is a `Function`.
*/
function isFunction(value){return typeof value == 'function';}
/**
* Checks if `obj` is a window object.
*
* @private
* @param {*} obj Object to check
* @returns {boolean} True if `obj` is a window obj.
*/
function isWindow(obj) {
return obj && obj.document && obj.location && obj.alert && obj.setInterval;
}
function isScope(obj) {
return obj && obj.$evalAsync && obj.$watch;
}
function isFile(obj) {
return toString.apply(obj) === '[object File]';
}
function isBoolean(value) {
return typeof value == 'boolean';
}
function trim(value) {
return isString(value) ? value.replace(/^s*/, '').replace(/s*$/, '') : value;
}
/**
* @ngdoc function
* @name angular.isElement
* @function
*
* @description
* Determines if a reference is a DOM element (or wrapped jQuery element).
*
* @param {*} value Reference to check.
* @returns {boolean} True if `value` is a DOM element (or wrapped jQuery element).
*/
function isElement(node) {
return node &&
(node.nodeName // we are a direct element
|| (node.bind && node.find)); // we have a bind and find method part of jQuery API
}
/**
* @ngdoc function
* @name angular.forEach
* @function
*
* @description
* Invokes the `iterator` function once for each item in `obj` collection, which can be either an
* object or an array. The `iterator` function is invoked with `iterator(value, key)`, where `value`
* is the value of an object property or an array element and `key` is the object property key or
* array element index. Specifying a `context` for the function is optional.
*
* Note: this function was previously known as `angular.foreach`.
*
<pre>
var values = {name: 'misko', gender: 'male'};
var log = [];
angular.forEach(values, function(value, key){
this.push(key + ': ' + value);
}, log);
expect(log).toEqual(['name: misko', 'gender:male']);
</pre>
*
* @param {Object|Array} obj Object to iterate over.
* @param {Function} iterator Iterator function.
* @param {Object=} context Object to become context (`this`) for the iterator function.
* @returns {Object|Array} Reference to `obj`.
*/
/**
* @private
* @param {*} obj
* @return {boolean} Returns true if `obj` is an array or array-like object (NodeList, Arguments, ...)
*/
function isArrayLike(obj) {
if (!obj || (typeof obj.length !== 'number')) return false;
// We have on object which has length property. Should we treat it as array?
if (typeof obj.hasOwnProperty != 'function' &&
typeof obj.constructor != 'function') {
// This is here for IE8: it is a bogus object treat it as array;
return true;
} else {
return obj instanceof JQLite || // JQLite
(jQuery && obj instanceof jQuery) || // jQuery
toString.call(obj) !== '[object Object]' || // some browser native object
typeof obj.callee === 'function'; // arguments (on IE8 looks like regular obj)
}
}
function forEach(obj, iterator, context) {
var key;
if (obj) {
if (isFunction(obj)){
for (key in obj) {
if (key != 'prototype' && key != 'length' && key != 'name' && obj.hasOwnProperty(key)) {
iterator.call(context, obj[key], key);
}
}
} else if (obj.forEach && obj.forEach !== forEach) {
obj.forEach(iterator, context);
} else if (isArrayLike(obj)) {
for (key = 0; key < obj.length; key++)
iterator.call(context, obj[key], key);
} else {
for (key in obj) {
if (obj.hasOwnProperty(key)) {
iterator.call(context, obj[key], key);
}
}
}
}
return obj;
}
function sortedKeys(obj) {
var keys = [];
for (var key in obj) {
if (obj.hasOwnProperty(key)) {
keys.push(key);
}
}
return keys.sort();
}
function forEachSorted(obj, iterator, context) {
var keys = sortedKeys(obj);
for ( var i = 0; i < keys.length; i++) {
iterator.call(context, obj[keys[i]], keys[i]);
}
return keys;
}
/**
* @ngdoc function
* @name angular.equals
* @function
*
* @description
* Determines if two objects or two values are equivalent. Supports value types, arrays and
* objects.
*
* Two objects or values are considered equivalent if at least one of the following is true:
*
* * Both objects or values pass `===` comparison.
* * Both objects or values are of the same type and all of their properties pass `===` comparison.
* * Both values are NaN. (In JavasScript, NaN == NaN => false. But we consider two NaN as equal)
*
* During a property comparision, properties of `function` type and properties with names
* that begin with `$` are ignored.
*
* Scope and DOMWindow objects are being compared only be identify (`===`).
*
* @param {*} o1 Object or value to compare.
* @param {*} o2 Object or value to compare.
* @returns {boolean} True if arguments are equal.
*/
function equals(o1, o2) {
if (o1 === o2) return true;
if (o1 === null || o2 === null) return false;
if (o1 !== o1 && o2 !== o2) return true; // NaN === NaN
var t1 = typeof o1, t2 = typeof o2, length, key, keySet;
if (t1 == t2) {
if (t1 == 'object') {
if (isArray(o1)) {
if ((length = o1.length) == o2.length) {
for(key=0; key<length; key++) {
if (!equals(o1[key], o2[key])) return false;
}
return true;
}
} else if (isDate(o1)) {
return isDate(o2) && o1.getTime() == o2.getTime();
} else {
if (isScope(o1) || isScope(o2) || isWindow(o1) || isWindow(o2)) return false;
keySet = {};
for(key in o1) {
if (key.charAt(0) === '$' || isFunction(o1[key])) continue;
if (!equals(o1[key], o2[key])) return false;
keySet[key] = true;
}
for(key in o2) {
if (!keySet[key] &&
key.charAt(0) !== '$' &&
o2[key] !== undefined &&
!isFunction(o2[key])) return false;
}
return true;
}
}
}
return false;
}
/**
* @description
* Determines the number of elements in an array, the number of properties an object has, or
* the length of a string.
*
* Note: This function is used to augment the Object type in Angular expressions. See
* {@link angular.Object} for more information about Angular arrays.
*
* @param {Object|Array|string} obj Object, array, or string to inspect.
* @param {boolean} [ownPropsOnly=false] Count only "own" properties in an object
* @returns {number} The size of `obj` or `0` if `obj` is neither an object nor an array.
*/
function size(obj, ownPropsOnly) {
var size = 0, key;
if (isArray(obj) || isString(obj)) {
return obj.length;
} else if (isObject(obj)){
for (key in obj)
if (!ownPropsOnly || obj.hasOwnProperty(key))
size++;
}
return size;
}
function includes(array, obj) {
return indexOf(array, obj) != -1;
}
function indexOf(array, obj) {
if (array.indexOf) return array.indexOf(obj);
for ( var i = 0; i < array.length; i++) {
if (obj === array[i]) return i;
}
return -1;
}
function arrayRemove(array, value) {
var index = indexOf(array, value);
if (index >=0)
array.splice(index, 1);
return value;
}