Nodejs Array Every every(fn, context)

Method Source Code

Array.prototype.every = function(fn, context) {
  if (typeof fn != "function") {
    throw new TypeError(fn + " is not a function");
  }/*from   w  w w .ja va2 s .  c o  m*/

  if (typeof context === 'undefined') {
    context = this;
  }

  for (var i = 0, l = this.length; i < l; i++) {
    if (this.hasOwnProperty(i) && !fn.call(context, this[i], i, this)) {
      return false;
    }
  }

  return true;
}

Related

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

   Array.prototype.every = Array.prototype.every || function(fun ) {
     "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 thisp = arguments[1];
     for (var i = 0; i < len; i++) {
       if (i in t && !fun.call(thisp, t[i], i, t)) return false;
   ...
   

2. 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)) {
   ...
   

3. 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));
   

4. 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;
   };