Nodejs Array Filter filter(predicateFunction)

Method Source Code

//http://reactivex.io/learnrx/
//Exercise 7: Implement filter()
//To make filtering easier, let's add a filter() function to the Array type. The filter() function accepts a predicate. A predicate is a function that accepts an item in the array, and returns a boolean indicating whether the item should be retained in the new array.
Array.prototype.filter = function(predicateFunction) {
   var results = [];
  this.forEach(function(itemInArray) {
    if (predicateFunction(itemInArray)) {
    results.push(itemInArray);/*w  w w  . j a v  a2 s.com*/
    }
  });
  return results;
};

console.log(JSON.stringify([1,2,3].filter(function(x) { return x > 2})));// === "[3]"

Related

1. filter(predicateFunction)

   Array.prototype.filter = function(predicateFunction) {
     var results = [];
     this.forEach(function(itemInArray) {
       if(predicateFunction(itemInArray) == true)
         results.push(itemInArray);
     });
     return results;
   };
   

2. filter(predicateFunction)

   Array.prototype.filter = function(predicateFunction){
     var result = [];
     this.forEach(function(item){
       if(predicateFunction(item)) {
         result.push(item);
     })
     return result;
   Array.prototype.map = function(predicateFunction){
     var result = [];
     this.forEach(function(item){
       result.push(predicateFunction(item));
     })
     return result;
   var a = [1,2,3,4,5,6,7,8,9];
   a.map(function(x){
     return x*2;
   }).filter(function(x){
     if(x > 4) return true;
   })
   

3. filter(predicateFunction)

   var result = ['A','B','C','D','E','F'].filter(function(x) { 
     return x > 'C'
   });
   console.log(result);
   var outcome = JSON.stringify(result);
   console.log(outcome);
   var testOutCome = outcome === '["D","E","F"]';
   console.log(testOutCome);
   

4. filter(predicateFunction)

   Array.prototype.filter = function(predicateFunction) {
     var results = [];
     this.forEach(function(itemInArray) {
       if (predicateFunction(itemInArray)) {
       results.push(itemInArray);
     });
     return results;
   };
   ...
   

5. filter(predicateFunction)

   Array.prototype.filter = function(predicateFunction) {
     var results = [];
     this.forEach(itemInArray => {
       if(predicateFunction(itemInArray)) {
          results.push(itemInArray);
     });
     return results;
   };
   ...
   

6. filter(predicateFunction)

   Array.prototype.filter = function(predicateFunction) {
     var results = [];
     this.forEach(function(item) {
       if (predicateFunction(item)) {
         results.push(item);
     });
     return results;
   

7. filter(search, func)

   Array.prototype.filter = function(search, func) {
     var results = [];
     for(var i = 0; i < this.length; i++) {
       if(func(search, this[i]))
          results.push(this[i]);
     return results;
   

8. filter(test)

   Array.prototype.filter = function (test) {
       var i, item, newArray = [];
       for (i = 0; i < this.length; i++) {
     item = this[i];
     if (test(item)) {
         newArray.push(item);
       return newArray;
   ...
   

9. filter(testFunction)

   Array.prototype.filter = function(testFunction){
     var result = [];
     this.forEach(function(item){
       if(testFunction(item)){
         result.push(item);
     })
     return result;