Check if an HTML input element is empty or has no value entered by user

Question

Related to this question here  Can I check if an element in the DOM has a value or not  I m trying to put it into an  if  statement and not sure if my approach is correct  Here goes   if  document getElementById  customx           do something     Or should it be   if  document getElementById  customx                 do something     EDIT  By value I mean  customx is a text input box  How can I check if this field has no text entered

User · Answer

var input   document getElementById  customx     if  input  amp  amp  input value        alert 1     else       alert  0

User · Answer

getElementById will return false if the element was not found in the DOM   var el   document getElementById  customx    if  el     null  amp  amp  el value               The element was found and the value is empty

User · Answer

The getElementById method returns an Element object that you can use to interact with the element  If the element is not found  null is returned  In case of an input element  the value property of the object contains the string in the value attribute   By using the fact that the  amp  amp  operator short circuits  and that both null and the empty string are considered  falsey  in a boolean context  we can combine the checks for element existence and presence of value data as follows   var myInput   document getElementById  customx    if  myInput  amp  amp  myInput value      alert  My input has a value

User · Answer

Your first one was basically right  This  FYI  is bad  It does an equality check between a DOM node and a string   if  document getElementById  customx             DOM nodes are actually their own type of JavaScript object  Thus this comparison would never work at all since it s doing an equality comparison on two distinctly different data types

User · Answer

You want   if  document getElementById  customx   value                do something     The value property will give you a string value and you need to compare that against an empty string

[javascript] Check if an HTML input element is empty or has no value entered by user

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