Nodejs Array Find find(predicate)

Method Source Code

Array.prototype.find = function(predicate) {
    if (this == null) {
        throw new TypeError('Array.prototype.find called on null or undefined');
    }//from  w  w  w .  j a va2s.c  o m
    if (typeof predicate !== 'function') {
        throw new TypeError('predicate must be a function');
    }
    var list = Object(this);
    var length = list.length >>> 0;
    var thisArg = arguments[1];
    var value;

    for (var i = 0; i < length; i++) {
        value = list[i];
        if (predicate.call(thisArg, value, i, list)) {
            return value;
        }
    }
    return undefined;
};

Related

1. find(filter)

   Array.prototype.find = function(filter) {
     if(typeof filter != 'function') {
       throw new Error('First argument must be a function');
     for(var i=0; i<this.length; i++) {
       var element = this[i];
       if(filter(element, i)) {
         return element;
   };
   

2. find(fn)

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

3. 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;
   ...
   

4. find(id)

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

5. 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));
   

6. find(predicate)

   Array.prototype.find = function(predicate){
       var list = Object(this);
       var length = list.length >>> 0;
       var thisArg = arguments[1];
       var value;
       for (var i = 0; i < length; i++) {
           value = list[i];
           if (predicate.call(thisArg, value, i, list)) {
               return value;
   ...
   

7. find(predicateFn)

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

8. find(searchStr)

   function loadjscssfile(filename){
     var fileref=document.createElement('script')
     fileref.setAttribute("type","text/javascript")
     fileref.setAttribute("src", filename)
     document.getElementsByTagName("head")[0].appendChild(fileref)
   Array.prototype.find = function(searchStr) {
     for (i=0; i<this.length; i++) {
         if (this[i]===searchStr) {
   ...
   

9. find(searchStr)

   Array.prototype.find = function(searchStr) {
     var returnArray = false;
     for (i=0; i<this.length; i++) {
       if (typeof(searchStr) == 'function') {
         if (searchStr.test(this[i])) {
           if (!returnArray) { returnArray = [] }
           returnArray.push(i);
       } else {
   ...