How to convert all elements in an array to integer in JavaScript?
JavascriptJavascript Problem Overview
I am getting an array after some manipulation. I need to convert all array values as integers.
My sample code
var result_string = 'a,b,c,d|1,2,3,4';
result = result_string.split("|");
alpha = result[0];
count = result[1];
// console.log(alpha);
// console.log(count);
count_array = count.split(",");
count_array
now contains 1,2,3,4
but I need these value to be in integers.
I had used parseInt(count_array);
, but it fails. JS considers each value in this array as string.
Javascript Solutions
Solution 1 - Javascript
ECMAScript5 provides a map
method for Array
s, applying a function to all elements of an array.
Here is an example:
var a = ['1','2','3']
var result = a.map(function (x) {
return parseInt(x, 10);
});
console.log(result);
Solution 2 - Javascript
You can do
var arrayOfNumbers = arrayOfStrings.map(Number);
For older browsers which do not support Array.map, you can use Underscore
var arrayOfNumbers = _.map(arrayOfStrings, Number);
Solution 3 - Javascript
var arr = ["1", "2", "3"];
arr = arr.map(Number);
console.log(arr); // [1, 2, 3]
Solution 4 - Javascript
You need to loop through and parse/convert the elements in your array, like this:
var result_string = 'a,b,c,d|1,2,3,4',
result = result_string.split("|"),
alpha = result[0],
count = result[1],
count_array = count.split(",");
for(var i=0; i<count_array.length;i++) count_array[i] = +count_array[i];
//now count_array contains numbers
You can test it out here. If the +
, is throwing, think of it as:
for(var i=0; i<count_array.length;i++) count_array[i] = parseInt(count_array[i], 10);
Solution 5 - Javascript
Just loop the array and convert items:
for(var i=0, len=count_array.length; i<len; i++){
count_array[i] = parseInt(count_array[i], 10);
}
Don't forget the second argument for parseInt.
Solution 6 - Javascript
The point against parseInt
-approach:
There's no need to use lambdas and/or give radix
parameter to parseInt
, just use parseFloat
or Number
instead.
Reasons:
-
It's working:
var src = "1,2,5,4,3"; var ids = src.split(',').map(parseFloat); // [1, 2, 5, 4, 3] var obj = {1: ..., 3: ..., 4: ..., 7: ...}; var keys= Object.keys(obj); // ["1", "3", "4", "7"] var ids = keys.map(parseFloat); // [1, 3, 4, 7] var arr = ["1", 5, "7", 11]; var ints= arr.map(parseFloat); // [1, 5, 7, 11] ints[1] === "5" // false ints[1] === 5 // true ints[2] === "7" // false ints[2] === 7 // true
-
It's shorter.
-
It's a tiny bit quickier and takes advantage of cache, when
parseInt
-approach - doesn't:// execution time measure function // keep it simple, yeah? > var f = (function (arr, c, n, m) { var i,t,m,s=n(); for(i=0;i++<c;)t=arr.map(m); return n()-s }).bind(null, "2,4,6,8,0,9,7,5,3,1".split(','), 1000000, Date.now); > f(Number) // first launch, just warming-up cache > 3971 // nice =) > f(Number) > 3964 // still the same > f(function(e){return+e}) > 5132 // yup, just little bit slower > f(function(e){return+e}) > 5112 // second run... and ok. > f(parseFloat) > 3727 // little bit quicker than .map(Number) > f(parseFloat) > 3737 // all ok > f(function(e){return parseInt(e,10)}) > 21852 // awww, how adorable... > f(function(e){return parseInt(e)}) > 22928 // maybe, without '10'?.. nope. > f(function(e){return parseInt(e)}) > 22769 // second run... and nothing changes. > f(Number) > 3873 // and again > f(parseFloat) > 3583 // and again > f(function(e){return+e}) > 4967 // and again > f(function(e){return parseInt(e,10)}) > 21649 // dammit 'parseInt'! >_<
Notice: In Firefox parseInt
works about 4 times faster, but still slower than others. In total: +e
< Number
< parseFloat
< parseInt
Solution 7 - Javascript
If you want to convert an Array of digits to a single number just use:
Number(arrayOfDigits.join(''));
Example
const arrayOfDigits = [1,2,3,4,5];
const singleNumber = Number(arrayOfDigits.join(''));
console.log(singleNumber); //12345
Solution 8 - Javascript
var inp=readLine();//reading the input as one line string
var nums=inp.split(" ").map(Number);//making an array of numbers
console.log(nums);`
input : 1 9 0 65 5 7 output:[ 1, 9, 0, 65, 5, 7 ]
what if we dont use .map(Number)
code
var inp=readLine();//reading the input as one line string
var nums=inp.split(" ");//making an array of strings
console.log(nums);
input : 1 9 0 65 5 7 output:[ '1', '9', '0', '65', '5', '7']
Solution 9 - Javascript
const arrString = ["1","2","3","4","5"];
const arrInteger = arrString.map(x => Number.parseInt(x, 10));
Above one should be simple enough,
One tricky part is when you try to use point free function for map as below
const arrString = ["1","2","3","4","5"];
const arrInteger = arrString.map(Number.parseInt);
In this case, result will be [1, NaN, NaN, NaN, NaN]
since function argument signature for map
and parseInt
differs
> map expects - (value, index, array)
where as parseInt expects -
> (value, radix)
Solution 10 - Javascript
How about this:
let x = [1,2,3,4,5]
let num = +x.join("")
Solution 11 - Javascript
Using jQuery, you can like the map()
method like so;
$.map(arr, function(val,i) {
return parseInt(val);
});