Applying a function to each object in a JavaScript array
JavascriptArraysJavascript Problem Overview
[ {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);
}
Javascript Solutions
Solution 1 - Javascript
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.
Solution 2 - Javascript
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);