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    Array every method Redirect 1

    Summary

    The every() method tests whether all elements in the array pass the test implemented by the provided function.

    Syntax

    arr.every(callback[, thisArg])

    Parameters

    callback
    Function to test for each element.
    thisArg
    Value to use as this when executing callback.

    Description

    The every method executes the provided callback function once for each element present in the array until it finds one where callback returns a falsy value (a value that becomes false when converted to a Boolean). If such an element is found, the every method immediately returns false. Otherwise, if callback returned a true value for all elements, every will return true. callback is invoked only for indexes of the array which have assigned values; it is not invoked for indexes which have been deleted or which have never been assigned values.

    callback is invoked with three arguments: the value of the element, the index of the element, and the Array object being traversed.

    If a thisArg parameter is provided to every, it will be passed to callback when invoked, for use as its this value.  Otherwise, the value undefined will be passed for use as its this value.  The this value ultimately observable by callback is determined according to the usual rules for determining the this seen by a function.

    every does not mutate the array on which it is called.

    The range of elements processed by every is set before the first invocation of callback. Elements which are appended to the array after the call to every begins will not be visited by callback. If existing elements of the array are changed, their value as passed to callback will be the value at the time every visits them; elements that are deleted are not visited.

    every acts like the "for all" quantifier in mathematics. In particular, for an empty array, it returns true. (It is vacuously true that all elements of the empty set satisfy any given condition.)

    Examples

    Example: Testing size of all array elements

    The following example tests whether all elements in the array are bigger than 10.

    function isBigEnough(element, index, array) {
      return (element >= 10);
    }
    var passed = [12, 5, 8, 130, 44].every(isBigEnough);
    // passed is false
    passed = [12, 54, 18, 130, 44].every(isBigEnough);
    // passed is true
    

    Polyfill

    every was added to the ECMA-262 standard in the 5th edition; as such it may not be present in other implementations of the standard. You can work around this by inserting the following code at the beginning of your scripts, allowing use of every in implementations which do not natively support it. This algorithm is exactly the one specified in ECMA-262, 5th edition, assuming Object and TypeError have their original values and that fun.call evaluates to the original value of Function.prototype.call.

    if (!Array.prototype.every)
    {
      Array.prototype.every = function(fun /*, thisArg */)
      {
        'use strict';
    
        if (this === void 0 || this === null)
          throw new TypeError();
    
        var t = Object(this);
        var len = t.length >>> 0;
        if (typeof fun !== 'function')
            throw new TypeError();
    
        var thisArg = arguments.length >= 2 ? arguments[1] : void 0;
        for (var i = 0; i < len; i++)
        {
          if (i in t && !fun.call(thisArg, t[i], i, t))
            return false;
        }
    
        return true;
      };
    }
    

    Specifications

    Specification Status Comment
    ECMAScript Language Specification 5.1th Edition (ECMA-262) Standard Initial definition.
    Implemented in JavaScript 1.6
    ECMAScript Language Specification 6th Edition (ECMA-262) Draft  

    Browser compatibility

    Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
    Basic support (Yes) 1.5 (1.8) 9 (Yes) (Yes)
    Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
    Basic support (Yes) (Yes) 1.0 (1.8) (Yes) (Yes) (Yes)

    See also

    Document Tags and Contributors

    Contributors to this page: Sheppy
    Last updated by: Sheppy,
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