Nodejs Array Every every(callback)

Method Source Code

Array.prototype.every = function every(callback) {
   if (this === undefined || this === null) {
      throw new TypeError(this + 'is not an object');
   }/*  w  w  w.  j a v a 2 s. c om*/

   if (!(callback instanceof Function)) {
      throw new TypeError(callback + ' is not a function');
   }

   var
   object = Object(this),
   scope = arguments[1],
   arraylike = object instanceof String ? object.split('') : object,
   length = Number(arraylike.length) || 0,
   index = -1;

   while (++index < length) {
      if (index in arraylike && !callback.call(scope, arraylike[index], index, object)) {
         return false;
      }
   }

   return true;
};

Related

1. every(fun /*, thisp*/)

   Array.prototype.every = Array.prototype.every || function(fun )  {
       var len = this.length >>> 0;
       if (typeof fun != "function") {
           throw new TypeError();
       var thisp = arguments[1];
       for (var i = 0; i < len; i++) {
           if (i in this &&
               !fun.call(thisp, this[i], i, this)) {
   ...
   

2. every(isOk)

   const array = [1, 42, 7, 9, 13, 10, 20, 35, 45, -7, -3, 0, 4, -1, 15];
   Array.prototype.every = function(isOk) {
     const len = this.length;
     for(let i = 0; i < len; i += 1) {
       console.log(isOk(this[i], i, this));
       if(!isOk(this[i], i, this)) {
         return false;
     return true;
   };
   Array.prototype.some = function(isOk) {
     const len = this.length;
     for(let i = 0; i < len; i += 1) {
       if(isOk(this[i], i, this)) {
         return true;
     return false;
   };
   console.log(array.some(x => x < 10));
   console.log(array.some(x => x > 100));
   console.log([1,2,3].some(x => x < 10));
   function isIncreasing(x, i, arr) {
     if(i === 0) {
       return true;
     return arr[i - 1] < x;
   console.log([1,2,3].every(isIncreasing));
   console.log([42, 1, 2, 3].every((x, i) => x % 2 === i % 2));
   

3. every(iterator)

   Array.prototype.every = function(iterator) {
     for (var i = 0, len = this.length; i < len; i++) {
       if (!iterator(this[i], i)) {
         return false;
     return true;
   };
   

4. everySyncasync (callback, thisArg)

   Array.prototype.everySync = async function (callback, thisArg) {
     for (let [index, item] of Object.entries(this)) {
       if (!await callback(item, index, this)) return false
     return true
   

5. every(callback)

   Array.prototype.every = function every(callback) {
     if (typeof callback !== 'function') {
       throw new TypeError(callback + ' is not a function');
     for (var array = this, index = 0, length = array.length; index < length; ++index) {
       if (index in array && !callback.call(arguments[1], array[index], index, array)) {
         return false;
     return true;
   };
   

6. every(callback)

   Array.prototype.every = function every(callback) {
     if (!(this instanceof Object)) {
       throw new TypeError(this + 'is not an object');
     if (typeof callback !== 'function') {
       throw new TypeError(callback + ' is not a function');
     var
     array = Object(this),
   ...
   

7. every(callback, scope)

   Array.prototype.every = function every(callback, scope) {
     for (var array = this, index = 0, length = array.length; index < length; ++index) {
       if (!callback.call(scope || window, array[index], index, array)) {
         break;
     return index === length;
   };