vinayakj vinayakj - 6 months ago 92
Javascript Question

Input number validation - Restrict to enter only numbers or digits, int & float both

How to restrict the input field to enter only numbers/digits int and float both.
Sometimes we need to allow both integer as well as float value for fields like amount, so in that case the validation is required. There are no of solutions available but they are of large size code. So need a short but effective code.

<p> Input box that accepts only valid int and float values.</p>
<input class="number-only" type=text />

Answer

No need for the long code for number input restriction just try this code.

It also accepts valid int & float both values.

Javascript Approach

onload =function(){ 
  var ele = document.querySelectorAll('.number-only')[0];
  ele.onkeypress = function(e) {
     if(isNaN(this.value+""+String.fromCharCode(e.charCode)))
        return false;
  }
  ele.onpaste = function(e){
     e.preventDefault();
  }
}
<p> Input box that accepts only valid int and float values.</p>
<input class="number-only" type=text />

jQuery Approach

$(function(){

  $('.number-only').keypress(function(e) {
	if(isNaN(this.value+""+String.fromCharCode(e.charCode))) return false;
  })
  .on("cut copy paste",function(e){
	e.preventDefault();
  });

});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<p> Input box that accepts only valid int and float values.</p>
<input class="number-only" type=text />

UPDATE

The above answers are for most common use case - validating input as a number.

But as per comments, some wants to allow few special cases like negative numbers & showing the invalid keystrokes to user before removing it, so below is the code snippet for such special use cases.

$(function(){
      
  $('.number-only').keyup(function(e) {
        if(this.value!='-')
          while(isNaN(this.value))
            this.value = this.value.split('').reverse().join('').replace(/[\D]/i,'')
                                   .split('').reverse().join('');
    })
    .on("cut copy paste",function(e){
    	e.preventDefault();
    });

});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<p> Input box that accepts only valid int and float values.</p>
<input class="number-only" type=text />