Check for Not Null

TODO: collapasable, copyable, download, etc

What is the idiomatic javascript to check if a value is not null and not undefined. false, 0, '' should pass the testIn JavaScript, to check if a value is not null and not undefined (while allowing values like false, 0, and '' to pass the test), you would typically use a strict inequality check against both null and undefined. However, since null and undefined are the only falsy values you want to exclude, you can use a comparison that leverages the fact that null and undefined are loosely equal to each other but not to any other falsy values. Here's how you do it:

if (value !== null && value !== undefined) {
  // Your code here: this block runs if value is anything other than null or undefined.
}

Alternatively, a more concise way to perform the same check is to use the strict inequality operator (!==) against undefined while taking advantage of the fact that null is loosely equal to undefined. This approach works because the loose equality check (== or !=) treats null and undefined as equal, but strict equality (=== or !==) does not:

if (value !== undefined && value !== null) {
  // This block will execute if `value` is anything other than `null` or `undefined`.
}

But if you prefer a more concise approach, leveraging the fact that both null and undefined are the only values that are equal to undefined under loose equality (==), you can simply write:

if (value != null) {
  // This block will execute if `value` is not `null` and not `undefined`.
}

This last example is idiomatic and takes advantage of JavaScript's type coercion rules to exclude both null and undefined in a single check, allowing all other values (including false, 0, and '') to pass the test.

Check for Not Null created at Tue Jan 20 1970 18:14:01 GMT+0000 (Coordinated Universal Time)