如何在JavaScript中将数组中的所有元素转换为整数？

Question

经过一些操作,我得到一个数组.我需要将所有数组值转换为整数.

我的示例代码

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现在包含1,2,3,4但我需要这些值是整数.

我曾经使用过parseInt(count_array);,但它失败了.JS将此数组中的每个值都视为字符串.

Answer 1

ECMAScript5 map为Arrays 提供了一种方法,将函数应用于数组的所有元素.这是一个例子:

var a = ['1','2','3']
var result = a.map(function (x) { 
  return parseInt(x, 10); 
});

console.log(result);

有关更多信息,请查看https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/map

Answer 2

你可以做

var arrayOfNumbers = arrayOfStrings.map(Number);

• MDN Array.prototype.map

对于旧的浏览器不支持Array.map,您可以使用下划线

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

Answer 3

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

Answer 4

您需要遍历并解析/转换数组中的元素,如下所示:

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

你可以在这里测试一下.如果+,投掷,将其视为:

for(var i=0; i<count_array.length;i++) count_array[i] = parseInt(count_array[i], 10);

Answer 5

只需循环数组并转换项目:

for(var i=0, len=count_array.length; i<len; i++){
    count_array[i] = parseInt(count_array[i], 10);
}

不要忘记parseInt的第二个参数.

Answer 6

反对点的parseInt方法:

没有必要使用lambdas和/或给出radix参数parseInt,只需使用parseFloat或Number代替.

原因:

1. 它的工作原理是:

   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
   

2. 它更短.

3. 它更快一点,并利用缓存,当parseInt-approach - 不:

     // 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'! >_<
   

注意:在Firefox中parseInt工作速度大约快4倍,但仍比其他速度慢.总数:+e< Number< parseFloat<parseInt

Answer 7

var inp=readLine();//reading the input as one line string
var nums=inp.split(" ").map(Number);//making an array of numbers
console.log(nums);`

输入：1 9 0 65 5 7 输出：[ 1, 9, 0, 65, 5, 7 ]

如果我们不使用怎么办 .map(Number)

代码

var inp=readLine();//reading the input as one line string
var nums=inp.split(" ");//making an array of strings
console.log(nums);

输入：1 9 0 65 5 7 输出：['1', '9', '0', '65', '5', '7']

Answer 8

如果要将数字数组转换为单个数字，只需使用：

Number(arrayOfDigits.join(''));

例子

const arrayOfDigits = [1,2,3,4,5];

const singleNumber = Number(arrayOfDigits.join(''));

console.log(singleNumber); //12345