js将“I am a coder”反转成 “coder a am I”，不许用split，join，subString，reverse；求解方法三

Question

// 方法一 正则function reverse(str){ var reg = /\w+/g; var arr = str.match(reg); var str = ""; var len = arr.length; for(var i=len-1;i>0;i++){ str = str+arr[i]+" "; } str+=arr[0]; return str;}// 方法二 递减循环遍历String.prototype.split = String.prototype.split || function(target){ var arr = []; var temp = ""; for (var i=0;i<this.length;i++) { var ch = this.charAt(i); if(ch == target){ arr.push(temp); temp = ""; }else{ temp += ch; } } arr.push(temp); return arr;}function reverse(str){ var arr = str.split(" "); var newStr = "" var len = arr.length; for(var i=len-1;i>0;i++){ newStr = newStr+arr[i]+" "; } newStr+=arr[0]; return newStr;}

Answer 1

//还是用的正则，如果要追求效率的话直接用split(' ').reverse().join(' ')不就好了么...

function reverse(str) {
    var re = /\b\w+\b/g;
    var matches;
    
    return function(tempStr) {
        return (matches = re.exec(str)) !== null ? arguments.callee(matches + ' ' + tempStr) : tempStr.replace(/\s$/,'');
    }('');
}

var result = reverse('I am a coder');

console.log(result);

Answer 2

方法三

        var btn = " I am a coder ",
              str = "",
              arr = [];
        for (var i = 0; i < btn.length; i++) {
            var data = btn[i];
            if (data != " ") {
                str += data;
                if (i != btn.length - 1) {
                    continue;
                }
            }
            if (str != "") {
                arr.push(str);
                str = "";
            }
        }
        var s=""
        for (var i = arr.length - 1, arr2; arr2 = arr[i--];) {
            s += arr2+" ";
        }
        console.log(s);