Unless you want to specifically check for undefined or null. In which case val != null will return true for undefined or null but not for other falsey values like 0.

Sep 5, 2017 · They are not equivalent. The first will execute the block following the if statement if myVar is truthy (i.e. evaluates to true in a conditional), while the second will execute the block if myVar is …

May 24, 2018 · The difference between those 2 parts of code is that, for the first one, every value that is not specifically null or an empty string, will enter the if. But, on the second one, every true-ish value …

How can I check for null values in JavaScript? I wrote the code below but it didn't work.

In order to understand, Let's analyze what will be the value return by the Javascript Engine when converting undefined , null and '' (An empty string also). You can directly check the same on your …

As many know, (0 == "") is true in JavaScript, but since 0 is a value and not empty or null, you may want to test for it. The following two functions return true only for undefined, null, empty/whitespace values …

Apr 1, 2011 · Is there a universal JavaScript function that checks that a variable has a value and ensures that it's not undefined or null? I've got this code, but I'm not sure if it covers all cases: …

Apr 25, 2013 · 16 The only value that doesn't equal itself in JavaScript is NaN. If null === null is false, then your JavaScript engine has serious problems ;) To make sure your conditional statement is well …

Dec 4, 2016 · It will not work for checking whether a non-global variable is null or undefined, nor will it work if your JavaScript is running outside a browser (i.e. in Node.js).

4 In short, a var is null when it's not pointing anywhere. In the other hand, a var equal to "" is a defined var pointing to a variable which contains an empty string. That's essentially different. As @jfriend00 …