如何在input中输入数字每三位加逗号

插件JQuery

HTML

$(function() {
    $('#dollar').on('keyup', function() {
        var a = $('#dollar').val();

        var b = TripartiteMethod(a);
        $(this).val(b);
    })

    function TripartiteMethod(num) {

        var type = true;
        var value = '';
        num = num.replace(/,/g, "");

        if (num.indexOf(".") < 0) {
            var t1 = num.toString().split('');

        } else {
            type = false;
            var arr = num.toString().split('.');
            var t1 = arr[0].toString().split('');
            var t2 = arr[1].toString();
        }

        var result = [],
            counter = 0;
        for (var i = t1.length - 1; i >= 0; i--) {
            counter++;
            result.unshift(t1[i]);
            if ((counter % 3) == 0 && i != 0) {
                result.unshift(',');
            }
        }

        if (type === true) {
            value = result.join('');
        } else {
            value = result.join('') + '.' + t2;
        }
        return value;
    }
})

如图：