javascript - javascript中的整数长度

Question

愚蠢的提问时间！

我知道在 JavaScript 中你必须将整数转换为字符串：

var num = 1024;
len = num.toString().length;
console.log(len);

我的问题是：为什么 JavaScript 中没有整数的长度属性？它是不经常使用的东西吗？

Answer 1

Well, I don't think providing length properties to number will be helpful. The point is the length of strings does not change by changing its representation.

for example you can have a string similar to this:

var b = "sometext";

and its length property will not change unless you actually change the string itself.

But this is not the case with numbers.

Same number can have multiple representations. E.g.:

 var a = 23e-1;
and 
 var b = 2.3;

So its clear that same number can have multiple representations hence, if you have length property with numbers it will have to change with the representation of the number.

Answer 2

您必须先设置变量toString()，如下所示：

var num = 1024,
str = num.toString(),
len = str.length;

console.log(len);

Answer 3

您可以使用 Math.log10(number) 找到数字的“长度”

var num = 1024;
var len = Math.floor(Math.log10(num))+1;
console.log(len);

或者如果您想与旧版浏览器兼容

var num = 1024;
var len = Math.log(num) * Math.LOG10E + 1 | 0; 
console.log(len);

与 Math.floor的| 0作用相同。