数字和一位小数的正则表达式

我似乎无法使用简单的正则表达式来工作。这是我目前所拥有的：

$(".Hours").on('input', function (e) {

    var regex = /^\d+(\.\d{0,2})?$/g;

    if (!regex.test(this.value)) {
        if (!regex.test(this.value[0]))
            this.value = this.value.substring(1, this.value.length);
        else
            this.value = this.value.substring(0, this.value.length - 1);
    }
});

我需要用户只能输入数字和一位小数（小数点后只有两位数字）。它现在工作正常，但用户不能以小数开头。

可接受：

23.53
0.43
1111.43
54335.34
235.23
.53 <--- Not working 

不可接受的：

0234.32 <--- The user can currently do this
23.453
1.343
.234.23
1.453.23

对此有什么帮助吗？

更新的答案：

RegExp -

^(?:0|[1-9]\d+|)?(?:.?\d{0,2})?$

解释于regex101:

原答案：

fiddle Demo

RegExp -

^(\d+)?([.]?\d{0,2})?$

解释

Assert position at the beginning of the string «^»
Match the regular expression below and capture its match into backreference number 1 «(\d+)?»
   Between zero and one times, as many times as possible, giving back as needed (greedy) «?»
   Match a single digit 0..9 «\d+»
      Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
Match the regular expression below and capture its match into backreference number 2 «([.]?\d{0,2})?»
   Between zero and one times, as many times as possible, giving back as needed (greedy) «?»
   Match the character “.” «[.]?»
      Between zero and one times, as many times as possible, giving back as needed (greedy) «?»
   Match a single digit 0..9 «\d{0,2}»
      Between zero and 2 times, as many times as possible, giving back as needed (greedy) «{0,2}»
Assert position at the end of the string (or before the line break at the end of the string, if any) «$»