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Fran Islas
Asked: 2020-10-30 16:19:56 +0800 CST 2020-10-30 16:19:56 +0800 CST

Regular expression to validate percentage on input (JavaScript)

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As the title says, I need to validate that the number entered in an input is suitable for a percentage. I'm trying to do it with a regular expression but so far I can't get it to work correctly. For example, when entering numbers without decimals, it tells me that it is incorrect, when it would be a valid value for a percentage.

Values ​​that I consider allowed:

  • Matches 100, 100.0 and 100.00
  • Numbers like 0, 15, 99, 3.1, 21.67
  • ,, letters or any other type of characters should NOT be allowed . Just numbers and a dot. Only precision of 2 decimal places maximum.

The regular expression that I managed to build and am using is:

 (^100(\.0{1,2})?$)|(^([1-9]([0-9])?|0)(\.[0-9]{1,2})?$)

Here is a small example of the code:

function checkValue(){
  var strporc = document.getElementById("txt_porcentaje").value
  var isValid =  strporc.match(/^(100(\.0{1,2})?|([0-9]?[0-9](\.[0-9]{1,2})))$/) == null ? false:true;
  console.log("Permitido: "+isValid);
 }
<label for="txt_porcentaje">Porcentaje:</label>
<input type="text" id="txt_porcentaje" oninput="checkValue();">

In advance thanks for the help!

javascript

1 Answers

  1. Best Answer

    Here is the working code:

    function checkValue(){
  var strporc = document.getElementById("txt_porcentaje").value
  var isValid =  strporc.match(/^((100(\.0{1,2})?)|(\d{1,2}(\.\d{1,2})?))$/) == null ? false:true;
  console.log("Permitido: "+isValid);
 }
    <label for="txt_porcentaje">Porcentaje:</label>
<input type="text" id="txt_porcentaje" oninput="checkValue();">

    I hope it helps you.

    Luck!

    • 2