javascript - 计算重复字符

Question

我想按输入顺序计算重复字符。这是我的代码。

<textarea id="field"></textarea>
<input type="submit" name="sub" id="sub" value="GO" />
<div id="charNum"></div>

和

$("#sub").click(function () {
    var all = "abcdefghijklmnopqrstuvwxyz";
    var str = $("#field").val();
    var text = "";
    for (var i = 0; i < all.length; i++) {
        var char = all.charAt(i);
        if (str.split(char).length > 1) text += str.split(char).length - 1 + "<br>";
    }
    $("#charNum").html(text);
});

如果我输入'mmani'，我会得到输出'1121'，它按字母顺序检查。我想要这样的输出:'2111'。

Answer 1

请查看代码中的注释以进行解释。

var k = "mamma mia miami".split('')

//if you want to exclude spaces
//var k = "mamma mia miami".split(/\s+/).join('').split('')

var p = {};
//count frequency of every character
for(var i=0;i<k.length;i++) {
    var currentChar = k[i];
    if(p[currentChar] == undefined) {
        //initialize counter for new char found
        p[currentChar]=1;
    } else {
        //increment counter for every next match for that char
        p[currentChar]++;
    }
}

var output = '';
//format output according to your need
for(each in p) {
    output += p[each]
}