如何在 JavaScript 中将数组中的所有元素转换为整数？

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最佳答案

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);

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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.

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ECMAScript5 provides a map method for Arrays, 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);

See Array.prototype.map()

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Using jQuery, you can like the map() method like so;

 $.map(arr, function(val,i) {
return parseInt(val);
});

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You can do

var arrayOfNumbers = arrayOfStrings.map(Number);

MDN Array.prototype.map

For older browsers which do not support Array.map, you can use Underscore

var arrayOfNumbers = _.map(arrayOfStrings, Number);

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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

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var arr = ["1", "2", "3"];
arr = arr.map(Number);
console.log(arr); // [1, 2, 3]

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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)

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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']

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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

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How about this:

let x = [1,2,3,4,5]
let num = +x.join("")

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use "join()"

let digits =[1,2,3,4]
let number =digits.join("")
console.log(number)

the '("")'- is used to indicate the separator,if you use 'digits.join("a")', it will give : 1a2a3a4