Nodejs Array Filter filter(predicateFunction)

Method Source Code

Array.prototype.filter = function(predicateFunction){
   var result = [];
   this.forEach(function(item){
      if(predicateFunction(item)) {
         result.push(item);/*from   ww  w . j  a v a  2 s. c o  m*/
      }
   })
   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;
})

Related

1. filter(predicate)

   Array.prototype.filter = function(predicate){
     return this.reduce(function(accumulator, value){
       return predicate(value) ? accumulator.concat(value) : accumulator;
     }, []);
   console.log([1, 2, 3, 4, 5].filter(function(val){
     return val % 2 === 0; 
   }));
   

2. filter(predicate)

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

3. filter(predicate)

   Array.prototype.filter = function(predicate) {
     var filtered_array = [];
     this.forEach(function (element, i) {
       if (predicate(element)) filtered_array.push(element);
     });
     return filtered_array;
   

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(function(itemInArray) {
       if(predicateFunction(itemInArray) == true)
         results.push(itemInArray);
     });
     return results;
   };
   

6. 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);
   

7. filter(predicateFunction)

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

8. filter(predicateFunction)

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

9. filter(predicateFunction)

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