An example explanation based on the input box covering the number in English

Example 1:

&lt;input type="text" value="0" onkeyup="cleartwoNum(this)"&gt;

//Limit input box input can only be numeric:function cleartwoNum(obj) {
   = (/[^\d]/g, '');
}

Example 2: You can enter the amount

&lt;input type="text" value="0" onkeyup="clearNoNum(this)"&gt;

//Limit input box input:function clearNoNum(obj) {
  //Replace all non-digits first, except for the numbers and.   = (/[^\d.]/g, "");
  //The first one must be guaranteed to be a number instead of.   = (/^\./g, "");
  //Certificate that only one appears, but no more.   = (/\.{2,}/g, ".");
  //Please guarantee. It only appears once, but not more than twice   = (".", "$#$").replace(/\./g, "").replace("$#$", ".");
}

The above example explanation based on the input box covering the English in English is all the content I share with you. I hope you can give you a reference and I hope you can support me more.