你不能，因为JS字符串是不可变的。短的非就地解决方案

[...str].reverse().join``

let str = "Hello World!"; Let r =[…str].reverse().join ' '; console.log (r);

使用Array函数，

String.prototype.reverse = function(){
    return [].reduceRight.call(this, function(last, secLast){return last + secLast});
}

真正的答案是:你不能把它颠倒过来，但是你可以创建一个颠倒过来的新字符串。

Just as an exercise to play with recursion: sometimes when you go to an interview, the interviewer may ask you how to do this using recursion, and I think the "preferred answer" might be "I would rather not do this in recursion as it can easily cause a stack overflow" (because it is O(n) rather than O(log n). If it is O(log n), it is quite difficult to get a stack overflow -- 4 billion items could be handled by a stack level of 32, as 2 ** 32 is 4294967296. But if it is O(n), then it can easily get a stack overflow.

有时候面试官还是会问你，“作为练习，你为什么不用递归来写呢?”就是这样:

String.prototype.reverse = function() {
    if (this.length <= 1) return this;
    else return this.slice(1).reverse() + this.slice(0,1);
}

测试运行:

var s = "";
for(var i = 0; i < 1000; i++) {
    s += ("apple" + i);
}
console.log(s.reverse());

输出:

999elppa899elppa...2elppa1elppa0elppa

为了尝试获得堆栈溢出，我在谷歌Chrome中将1000更改为10000，它报告:

RangeError: Maximum call stack size exceeded

你不能将字符串反向，但你可以使用这个:

String.prototype.reverse = function() { 返回this.split (" ") .reverse () . join (" "); ｝ var s = "ABCD"; S = S .reverse(); console.log(年代);

下面是一个基本的ES6不可变的例子，没有使用Array.prototype.reverse:

//:: reverse = String ->字符串 const reverse = s => []. reduceright .使用实例调用(s， (a, b) => a + b) Console.log (reverse('foo')) // => 'oof' Console.log (reverse('bar')) // => 'rab' Console.log (reverse('foo-bar')) // => ' rabb -oof'

以下是可以用来实现字符串反转的四种最常用方法

给定一个字符串，返回一个新字符串 字符顺序

问题的多种解决方案

//reverse('apple') === 'leppa'
//reverse('hello') === 'olleh'
//reverse('Greetings!') === '!sgniteerG'

// 1. First method without using reverse function and negative for loop
function reverseFirst(str) {
    if(str !== '' || str !==undefined || str !== null) {
        const reversedStr = [];
        for(var i=str.length; i>-1; i--) {
        reversedStr.push(str[i]);
        }
    return reversedStr.join("").toString();
    }
}

// 2. Second method using the reverse function
function reverseSecond(str) {
    return str.split('').reverse().join('');
}

// 3. Third method using the positive for loop
function reverseThird(str){
    const reversedStr = [];
    for(i=0; i<str.length;i++) {
        reversedStr.push(str[str.length-1-i])
    }
    return reversedStr.join('').toString();
}

// 4. using the modified for loop ES6
function reverseForth(str) {
    const reversedStr = [];
    for(let character of str) {
        reversedStr = character + reversedStr;
    }
    return reversedStr;
}

// 5. Using Reduce function
function reverse(str) {
    return str.split('').reduce((reversed, character) => {
        return character + reversed;  
    }, '');
}