CODEWITHSUNDEEP
javascripttypescript
Feber Castellon
Feber Castellon

Reputation: 579

Fix a check null method in Typescript or Javascript

I have this code for my check method:

   static emptyOrWhiteSpaceString(obj: string, paramName: string) {
    if (obj === null || obj === '' || obj === ' ') {
        throw new ServiceException(`${paramName} name is empty.`);
     }
   }

and I got this suggestion from a reviewer in my pull request:

if (!obj || !obj.trim())

enter image description here

I understand what he wants, but I don't understand the way he is saying it. Please help, how to fix this code according to this answer?

Upvotes: 0

Views: 78

Answers (2)

Qpirate
Qpirate

Reputation: 2078

(obj === null || obj === '' || obj === ' ') does not check for the instances of undefined or when a string has more than one space. your reviewer has fixed both of those issues with his comment.

JS considers most things an object, so the !obj will test for if the item is actually an object (i.e. not null or undefined or empty)

the obj.trim() will trim all the whitespace around the string, and if it is empty will return false. this is because an empty string in JS can be converted to a boolean false, ! in this will convert it to true.

Upvotes: 0

Rajitha Udayanga
Rajitha Udayanga

Reputation: 1732

static emptyOrWhiteSpaceString(obj: string, paramName: string) {

    // change if condition checkes like this
    if (!obj || !obj.trim()) {
        throw new ServiceException(`${paramName} name is empty.`);
     }
   }

Upvotes: 1

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