javascript - 用if，for怎么改写下面的小测试

Question

    var box = "Mr.Lee Lee Lee Lee"
    var boxarr = [];
    var pos = box.indexOf("L");
    while(pos > -1){
        boxarr.push(pos);
        pos = box.indexOf("L",pos + 1);
    }
    console.log(boxarr);

--！尝试改了好几次，都不成功，求大神。
把box变量里的L的索引都弄到数组boxarr打印出来

Answer 1

var box = "Mr.Lee Lee Lee Lee";
var boxarr = [];
for(var i=0; i<box.length; i++) {
    if (box[i] == 'L') {
        boxarr.push(i);
    }
}

Answer 2

var box = "Mr.Lee Lee Lee Lee"
var boxarr = [];
for (var i = box.indexOf("L"); i > -1; i = box.indexOf("L", i + 1)) {
    boxarr.push(i);
}
console.log(boxarr);

Answer 3

var box = "Mr.Lee Lee Lee Lee";
var boxarr=[];

var splitBox=box.split("L");
var len=splitBox.length-1;
for(var i=0;i<len;i++){
    var pos=i;
    for(var j=0;j<=i;j++){
        pos+=splitBox[j].length;
    }
    boxarr.push(pos);
}

console.log(boxarr);