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.
This question is related to
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']
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
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)
Using jQuery, you can like the map()
method like so;
$.map(arr, function(val,i) {
return parseInt(val);
});
var arr = ["1", "2", "3"];_x000D_
arr = arr.map(Number);_x000D_
console.log(arr); // [1, 2, 3]
_x000D_
If you want to convert an Array of digits to a single number just use:
Number(arrayOfDigits.join(''));
const arrayOfDigits = [1,2,3,4,5];
const singleNumber = Number(arrayOfDigits.join(''));
console.log(singleNumber); //12345
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);
_x000D_
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.
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);
How about this:
let x = [1,2,3,4,5]
let num = +x.join("")
Source: Stackoverflow.com