Description:

Reverse digits of an integer.
Example1: x = 123, return 321Example2: x = -123, return -321
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**Note:
**The input is assumed to be a 32-bit signed integer. Your function should return 0 when the reversed integer overflows.

My code:

/**
 * @param {number} x
 * @return {number}
 */
var reverse = function(x) {
   let str = x.toString();
    if(x >= 0) {
        var temp = parseInt(str.split("").reverse().join(""));
        if(temp >= Math.pow(2, 31)) {
           return 0;
           } else {
           return temp;
           }
    } else {
        var temp = str.slice(1, str.length).split("").reverse().join("");
        if(temp > Math.pow(2, 31)) {
            return 0;
        } else {
            return parseInt("-" +temp);
        }
    }
};

Note: 主要是要了解IEEE 754格式带符号整数的取值范围是-2^31~2^31-1，对已经反序的数字判断，不在范围就返回0即可