正则匹配输入小数点后两位，

`

<input change="" type="text" />
<button onclick="dianwo(event)">点我</button>
  var a = document.getElementsByTagName('input')
function dianwo(e) {
    var value = a[0].value
    value = value.replace(/[^\d.]/g, '').replace(/\.{2,}/g, '.').replace('.', '$#$').replace(/\./g, '').replace('$#$', '.').replace(/^(\-)*(\d+)\.(\d\d).*$/, '$1$2.$3').replace(/^\./g, '')
    console.log(value)
        // console.log(value)
}

`