Nodejs Array Find find(filter)

Method Source Code

Array.prototype.find = function(filter) {
  if(typeof filter != 'function') {
    throw new Error('First argument must be a function');
  }/*from  w w  w . j  a  va 2  s. c  o  m*/
  for(var i=0; i<this.length; i++) {
    var element = this[i];
    if(filter(element, i)) {
      return element;
    }
  }
};

Related

1. find(criteria)

   Array.prototype.find = function(criteria) {
     for (var i = 0; i < this.length; i++) {
       if (criteria(this[i])) {
         return this[i]
     return null
   Math.sign = function(x) {
   ...
   

2. find(element)

   Array.prototype.find = function (element) {
     if (typeof element === 'function') {
       return element(this);
     var len = this.length;
     for (var i = 0; i < len; i++) {
       if(this[i] === element) {
         return element;
     return -1;
   var doPow = function (array) {
     var len = array.length;
     for(var i = 0; i < len; i++) {
       array[i] *= array[i]; 
     return array;
   var b = [1, 2, 3, 4, 5, 6];
   console.log(b.find(doPow));
   

3. find(element)

   Array.prototype.find = function(element) {
       var i;
       for (i = 0; i < this.length; i += 1) {
           if (this[i] === element) {
               return i;
       return false;
   

4. find(element)

   Array.prototype.find=function(element){
       var i;
       for(i=0;i<this.length;i+=1){
           if(this[i]===element){
               return i;
       return false;
   Array.prototype.remove=function(element){
       var i;
       for(i=0;i<this.length;i+=1){
           if(this[i]===element){
               this.splice(i,1)
               return true;
       return false;
   var arr=['a','b','c','d','e','f','g','h'];
   arr.remove('e');
   arr.remove('f');
   var i;
   for(i=0;i<arr.length;i+=1){
       console.log(arr[i]);
   

5. find(f)

   Array.prototype.find = function(f) {
     for (var i = 0; i < this.length; i++) {
       if (f(this[i]))
         return this[i];
   };
   

6. find(fn)

   Array.prototype.find = function(fn) {
       for (var i = 0; i < this.length; i++) {
           if (fn(this[i])) {
               return this[i];
   

7. find(fn, v)

   Array.prototype.find = function(fn, v) {
       var isFN = typeof(fn) === 'function';
       var isV = v !== undefined;
       for (var i = 0, len = this.length; i < len; i++) {
           if (isFN) {
               if (fn(this[i], i)) {
                   return this[i];
               continue;
   ...
   

8. find(id)

   Array.prototype.find = function(id) {
     return this.filter(function(a) {
       if ( a.id == id ) {
         return a;
     }).first();
   

9. find(isOk)

   const array = [1, 42, 7, 9, 13, 10, 20, 35, 45, -7, -3, 0, 4, -1, 15];
   Array.prototype.find = function(isOk) {
     const len = this.length;
     for(let i = 0; i < len; i += 1) {
       if(isOk(this[i], i, this)) {
         return this[i];
   Array.prototype.findIndex = function(isOk) {
     const len = this.length;
     for(let i = 0; i < len; i += 1) {
       if(isOk(this[i], i, this)) {
         return i;
     return -1;
   console.log(array.find(x => x % 2 === 0));
   console.log(array.find(x => x % 2 === 1));
   console.log(array.find(x => x > 10 && x < 20));
   console.log(array.find(x => x === 45));
   console.log(array.find(x => x === 46));
   console.log(array.findIndex(x => x % 2 === 0));
   console.log(array.findIndex(x => x % 2 === 1));
   console.log(array.findIndex(x => x > 10 && x < 20));
   console.log(array.findIndex(x => x === 45));
   console.log(array.findIndex(x => x === 46));