Single character variable names affect code readability and complicate code refactoring, because of the difficulty in searching and replacing single characters.

This issue will not be raised for certain special identifiers, such as i, j or n. It will also not be reported for the parameters used in for and while loops.

Bad Practice

var a;
const l = 90

Recommended

var age;
const limit = 90;


for(let o = 2; o < 10; o++){
    sum += o
}