CODEWITHSUNDEEP
javascriptreactjstypescript
Kasper Hansen
Kasper Hansen

Reputation: 6557

Check for empty of null in javascript

I had a bug that turned out to be because I forgot to check for null values. I added the check, but would like if it could be written more concise.

<ListItem onClick={!pattern.capped && !pattern.hasInlineRef ? search(pattern.dbValue, pattern.dbValue === "" || pattern.dbValue === null) : undefined}>

Can this check for empty or null be shortened?

search(pattern.dbValue, pattern.dbValue === "" || pattern.dbValue === null)

It's written in Typescript, but I guess the curly braces make it JavaScript.

Upvotes: 1

Views: 152

Answers (2)

govardhan n
govardhan n

Reputation: 1

You can create an helper function in a separate folder and pull out this function into the files where you need to check for null, undefined, empty string or an empty object.You can write something like this:

export default value =>
value === undefined ||
value === null ||
(typeof value === 'object' && Object.keys(value).length === 0) ||
(typeof value === 'string' && value.trim().length === 0);

Hope this helps

Upvotes: 0

thortsx
thortsx

Reputation: 2280

First, you can create an util function to check null, empty or undefined:

export function isNullOrEmpty(value) {
    return (value === null || value === undefined || value === "") ? true : false 
}

Or, you can fast test with falsy and truthy:

search(pattern.dbValue, !pattern.dbValue)

List of falsy values in JavaScript: MDN Falsy

  1. false
  2. null
  3. undefined
  4. 0
  5. NaN
  6. ''
  7. document.all

Upvotes: 2

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