原生JavaScript实现反转字符串中单词内的字母位置

    //方法Ⅰ
    const res=()=>{
        let str = 'abcdefg hijklmn opqrst'
        const arr= str.split('')
        let newArr=[]
        for(let i=0;i<arr.length;i++){
            newArr[i]=arr[arr.length-1-i]
        }
        newArr = newArr.join('').split(' ')
        let newArr1=[]
        for(let i=0;i<newArr.length;i++){
            newArr1[i]=newArr[newArr.length-1-i]
        }
        newArr1 = newArr1.join(' ')
        return newArr1;
    }
    console.log('方法Ⅰ')
    console.log('输入：abcdefg hijklmn opqrst')
    console.log('输出：'+res())
//====================================================================================
    //方法Ⅱ---直接遍历
var reverseWords = function (s) {
    const ret = []
    const arr_length = s.length
    let i = 0
    while (i < arr_length) {
        let start = i
        while (i < arr_length && s[i] != " ") { //找每次的单词的起止位置
            i++
        }
        for (let p = start; p < i; p++) { //从后向前遍历
            ret.push(s.charAt(start + i - 1 - p))
        }
        while (i < arr_length && s[i] == " ") { //push空格
            i++;
            ret.push(" ")
        }
    }
    return ret.join("")
};
var s = "Let take LeetCode contest"
console.log('方法Ⅱ')
console.log('输入：Let take LeetCode contest')
console.log('输出：'+reverseWords(s))
//====================================================================================
//方法Ⅲ
var reverseWords = function(s) {
    let arr =  s.split(' ')
    const reverseString = (str) => {
        if(!str) return str
        str = str.split('')
        let temp 
        for(let i = 0 ; i < str.length>>1 ; i++){
            temp = str[i]
            str[i] = str[str.length-1-i]
            str[str.length-1-i] = temp
        }
        return str.join('')
    }

    let str = ''
    for(let i =  0 ; i < arr.length ; i++){
        let fillStr = ' '
        if(i == arr.length - 1) fillStr = ''
        str+= reverseString(arr[i]) + fillStr
    }
    return str
   
};
var s = "12345 6789"
console.log('方法Ⅲ')
console.log('输入：12345 6789')
console.log('输出：'+reverseWords(s))
//====================================================================================
//方法Ⅳ、双指针
var reverseWords = function(s) {
    let start = 0 , end = 1, arr = []
    //处理空格
    s+= ' '
    while(end < s.length){
        if(s[end] == ' '){
            for(let i = end - 1; i >= start ; i--){
                arr.push(s[i])
            }
            //处理空格
            if(end !== s.length - 1) arr.push(' ')
            start = end+1
        }
        end++
    }
    return arr.join('')
}
var s = "abcde fghijk"
console.log('方法Ⅳ')
console.log('输入：abcde fghijk')
console.log('输出：'+reverseWords(s))