Comparing String to null or empty values in JavaScript

Question

i am trying to create an if and else statement in JavaScript wherein if the string is empty, it will send out an alert box that all forms must be filled up. If not, the data grid in the webpage will increment with all the information entered on the form. But it seems that my code is not working properly. Below is my javascript code

function addData(){ 
  if(document.getElementById("txt_description").isEmpty || document.getElementById("txt_update").isEmpty){
    alert("Missing information!!! Please fill up all the blank items"); 
  }else{
    var table = document.getElementById("myTable");
    var row = table.insertRow(-1);
    var cell1 = row.insertCell(0);
    var cell2 = row.insertCell(1);
    var cell3 = row.insertCell(2);
    var cell4 = row.insertCell(3);
    var cell5 = row.insertCell(4);
    var cell6 = row.insertCell(5);
   
    cell1.innerHTML = document.getElementById("input_name").value;
    cell2.innerHTML = document.getElementById("input_blank2").value;
    cell3.innerHTML = document.getElementById("txt_description").value;
    cell4.innerHTML = document.getElementById("input_status").value;
    cell5.innerHTML = document.getElementById("input_pageable").value;
    cell6.innerHTML = document.getElementById("txt_update").value;
    
  }
}

So what does `.isEmpty` do, there's no such property natively? — adeneo, Oct 14 '16 at 00:55
Possible duplicate of [Is there a standard function to check for null, undefined, or blank variables in JavaScript?](http://stackoverflow.com/questions/5515310/is-there-a-standard-function-to-check-for-null-undefined-or-blank-variables-in) — BrTkCa, Oct 14 '16 at 00:59

James111 · Accepted Answer · 2016-10-14T01:07:52.060

1

Change your if statement to this:

if(document.getElementById("txt_description").value == ""|| document.getElementById("txt_update").value == "")

.isEmpty does not exist in javascript! If your input is empty, comparing it to an empty string will be sufficient!

For dealing with null values:

if(document.getElementById("txt_description").value == ""|| 
document.getElementById("txt_update").value == "" || 
document.getElementById("txt_description").value == null || 
document.getElementById("txt_update").value == null)

EDIT:

As mentioned in one of the comments, .value cannot be null. So you cold simply use the following if statement:

if(document.getElementById("txt_description").value == ""|| 
    document.getElementById("txt_update").value == "")

edited Oct 14 '16 at 01:07

answered Oct 14 '16 at 00:59

James111

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This won't work, because `document.getElementById` will return either an element or `null`, but never an empty string `""`, so it will always be false. I think you meant `document.getElementById().value`? – RobertAKARobin Oct 14 '16 at 01:02
Edited @RobertAKARobin – James111 Oct 14 '16 at 01:05
Thank you James and Robert! I added what Robert commented on this post with your code and it is perfectly working now. Thanks a lot guys! – jdog123 Oct 14 '16 at 01:05
1

`value` will never be `null`. – charlietfl Oct 14 '16 at 01:05
Yup i did! apparently there is this timer when I can click the check the "accepted" button. Thanks robert – jdog123 Oct 14 '16 at 01:08

Comparing String to null or empty values in JavaScript

1 Answers1