ESLint error no-unneeded-ternary

Question

ESLint is telling me this error message inside my JS module: error no-unneeded-ternary Unnecessary use of conditional expression for default assignment

The error comes in the get method on the return statement return val ? val : defaultVal;?

import ls from 'local-storage';

export default {
    get(key, defaultVal = null) {
        var val = ls(key);
        return val ? val : defaultVal;
    },

    set(key, val) {
        return ls(key, val);
    },

    remove(key) {
        return ls.remove(key);
    },
};

Any idea why do I get this error message? I have found some resource on ESLint's website regarding this error message here but it applies to boolean expressions and I can not figure out why would that apply to my code...

score 84 · Accepted Answer · answered Feb 29 '16 at 14:42

84

You don't need a ternary when a simple val || defaultVal will do.

answered Feb 29 '16 at 14:42

Dave Newton

156,572
25
250
300

@UmakantPatil Those aren't equivalent. – Dave Newton Sep 13 '17 at 10:19
1

@UmakantPatil Once you make them actually do the same thing the differences are (a) browser-dependent, and (b) within 1-3%. It's also shorter and clearer; unless you're in a very tight game loop or similar it's a pointless micro-optimization. In any case, the original question was regarding the ESLint warning which defaults to flagging ternaries in default value assignments. ¯\(°_o)/¯ – Dave Newton Sep 13 '17 at 15:31
Oh right. my bad. I didn't do the assignments in one case. Thanks! – Umakant Patil Sep 27 '17 at 08:59

score 17 · Answer 2 · answered Feb 02 '20 at 08:07

17

// Bad
foo(bar ? bar : 1);

// Good
foo(bar || 1);

This is how they say in Es-lint

answered Feb 02 '20 at 08:07

Charith Jayasanka

2,745
20
35

ESLint error no-unneeded-ternary

2 Answers2

Linked