编写一个函数isMerge，判断一个字符串str是否可以由其

function isMerge(s, part1, part2) {
    var p1 = part1.split(''),
	p2 = part2.split('');

    for(var i = 0, length1 = s.length; i < length1; i++){
	    if (p1.indexOf(s[i]) > -1) {
	        p1.shift();
	    } else if (p2.indexOf(s[i]) > -1) {
	        p2.shift();
	    } else {
	        return false;
	    }
    }
    return true;
} 

function isMerge(s, part1, part2) {
	var sArray = new Array();
	if(s.length == part1.length + part2.length)
	{
		//var parrays = s.split("");
		var parray1 = part1.split("");
		var parray2 = part2.split("");
		console.log(parray1);
		console.log(parray2);
		for(var ai = 0;ai<part1.length;ai++)
		{
			if(s.indexOf(parray1[ai])!= -1)
			{
				sArray.push(s.indexOf(parray1[ai]));
			}
		}
		for(var bi = 0;bi<part2.length;bi++)
		{
			if(s.indexOf(parray2[bi])!= -1)
			{
				sArray.push(s.indexOf(parray2[bi]));
			}
		}
	}
	
	sArray = sArray.unque();
	console.log(sArray);
	if(sArray.length == s.length )
	{
		console.log("成功了");
	}
	else
	{
		console.log("失败");
	}
	
}

Array.prototype.unque = function(){
	var json = [];
	var newArray = new Array();
	for(var i = 0; i < this.length; i++){
		if(json[this[i]]!=1)
		{
			json[this[i]] = 1;
			newArray.push(this[i]);
		}
	}
	return newArray;
}

var a1 = "codewars";
var a2 = "cdw";
var a3 = "oears";

isMerge(a1,a2,a3);

function isMerge(s, part1, part2){
    var s1 = [];
    var s2 = [];
    for(var i=0, len=s.length; i<len; i++){
        if(part1.indexOf(s[i])>-1) s1.push(s[i]);
        else if(part2.indexOf(s[i])>-1) s2.push(s[i]);
        else return false;
    }
    s1.forEach(function(item){
        if(part1.indexOf(item) != s1.indexOf(item)) return false;
    })
    s2.forEach(function(item){
        if(part2.indexOf(item) != s2.indexOf(item)) return false;
    })    

    return true;
}

function isMerge(s, p1, p2){
	var i = 0, j = i;
	while (i < p1.length && i < p2.length){
		if (s[j] == p1[i] && s[++j] == p2[i]){
			i++;
			j++;
		}else{
			return false;
		}
	}

	while (i < p1.length){
		if (p1[i] != s[j]){
			return false;
		}
		i++;
		j++;
	}

	while (i < p2.length){
		if (p2[i] != s[j]){
			return false;
		}
		i++;
		j++;
	}

	return true;
}

function isMerge(s, part1, part2) { if(s.length==part1.length+part2.length){ var j=0,k=0; for(var i=0;i<s.length;i++){ if(s[i]==part1[j] && j<part1.length){ j++;
            }else if (s[i]==part2[k] && k<part2.length){ k++;
            }else { return false;
            }
        } return true;
    }else { return false;
    }
}

function inMerge(s,part1,part2){
    var len = s.length;
    var part1len = part1.length;
    var part2len = part2.length;
    var point1 = 0;
    var point2 = 0;
    while(len >= 0 && (point1<=part1len || point2<=part2len)){
        if(part1[point1] == s[0]){
            s=s.slice(1);
            len--;
            point1++;
        }else if(part2[point2] == s[0]){
            s=s.slice(1);
            len--;
            point2++;
	}else{
            point1++;
            point2++;
	}
    }
    if(len >0)
        return false;
    else
        return true;
}

function isMerge(s, part1, part2){
    var part1Arr = part1.split('');
    var part2Arr = part2.split('');
    var part1Count = [];
    var part2Count = [];
    function countArr(tmp) {
       var result = [];
       for(var i = 0; i < tmp.length; i++) {
            var idx = s.indexOf(tmp[i]);
            if(idx != -1) {
                result.push(idx);
            }
        }
        return result;
    }
    function minOrder(temp) {
        for(var i = 0; i < temp.length; i++) {
            if(temp[i] > temp[i+1]){
                return false;
            }
        }
        return true;
    }
    part1Count = countArr(part1Arr);
    part2Count = countArr(part2Arr); 
    if((part1Count.length + part2Count.length) != s.length){
         console.log("s 不由 part1和part2 组成");
    }else{
        if(minOrder(part1Count) && minOrder(part2Count)){
         console.log("s由part1和part2组成")
        }
    }
}