383. Ransom Note

Given an arbitrary ransom note string and another string containing letters from all the magazines, write a function that will return true if the ransom note can be constructed from the magazines ; otherwise, it will return false.

Each letter in the magazine string can only be used once in your ransom note.

Note:
You may assume that both strings contain only lowercase letters.

canConstruct("a", "b") -> false
canConstruct("aa", "ab") -> false
canConstruct("aa", "aab") -> true

使用变查找边替换的方法

var canConstruct = function(ransomNote, magazine) {
    var num = ransomNote.length;
    for (var i = 0; i<num; i++) {
        var index = magazine.indexOf(ransomNote[i]);
        if (index===-1) {
            return false;
        } else {
            magazine = magazine.replace(ransomNote[i],'');
        }
    }
    return true;
};