Applying a function to each object in a JavaScript array

Question

[ {name:'hi',data:'1,2,3,4,5'} , {name:'hello',data:'5,4,3,2,1'} ] 

What I need is to apply a split on data of each object in array so that the result would be:

[ {name:'hi',data:[1,2,3,4,5]} , {name:'hello',data:[5,4,3,2,1]} ] 

I know I can loop through the array using for each and produce a new array, but is there a better, faster method?

var arr = [{     name: 'hi',     data: '1,2,3,4,5' }, {     name: 'hello',     data: '5,4,3,2,1' }];  var new_arr = []; for (i in arr) {     var temp = {};     temp.name = arr[i].name;     temp.data = arr[i].data.split(',');     new_arr.push(temp); } 

Answer 1

You could use Array.prototype.map:

var new_array = old_array.map(function(e) {    e.data = e.data.split(',');    return e; }); 

As the comment said, this way changes the old_array. You could also return a new object in the callback function without changing the original array.

Answer 2

var data = [{     name: 'hi',     data: '1,2,3,4,5' }, {     name: 'hello',     data: '5,4,3,2,1' }]; 

You can use the Array.prototype.map on data to construct a new Array, like this

var result = data.map(function (currentObject) {     return {         name: currentObject.name,         data: currentObject.data.split(",").map(Number)     }; }); 

Here, we split the currentObject.data based on , and then we call Number function on all the split strings, so that you will get the result object's data as numbers, as you wanted in the question.

Output

[{     name: 'hi',     data: [1, 2, 3, 4, 5] }, {     name: 'hello',     data: [5, 4, 3, 2, 1] }] 

let data = [{     name: 'hi',     data: '1,2,3,4,5'   }, {     name: 'hello',     data: '5,4,3,2,1'   }],   result = data.map(function(currentObject) {     return {       name: currentObject.name,       data: currentObject.data.split(",").map(Number)     };   }); console.log(result);