Checking if a textbox is empty in Javascript

Question

This is my code which was supposed to raise an alert message if the textbox is left empty   function a id        var n document getElementById id  value      if  n length  lt  1                window alert  Field is blank            return false            The bug I m getting is that the field is not getting verified onChange the first time  But when the text box is filled with some data and erased  now the OnChange fires  and the alert message is displayed  How can I fix this bug

User · Answer

your validation should be occur before your event suppose you are going to submit your form.

anyway if you want this on onchange, so here is code.

function valid(id)
{
    var textVal=document.getElementById(id).value;
    if (!textVal.match(/\S/)) 
    {
        alert("Field is blank");
        return false;
    } 
    else 
    {
        return true;
    }
 }

User · Answer

function valid id                var textVal document getElementById id  value          if   textVal match  quot Tryit quot                          alert  quot Field says Tryit quot                return false                     else                        return true                    Use this for expressing things

User · Answer

onchange will work only if the value of the textbox changed compared to the value it had before  so for the first time it won t work because the state didn t change   So it is better to use onblur event or on submitting the form    x000D   x000D  function checkTextField field    x000D    document getElementById  error   innerText   x000D       field value            Field is empty      Field is filled    x000D    x000D   lt input type  text  onblur  checkTextField this      gt  x000D   lt p id  error  gt  lt  p gt  x000D   x000D   x000D     Or old live demo

[javascript] Checking if a textbox is empty in Javascript

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