Node js ternary operator why comparsion goes wrong?

Question

i have problem with ternary operator comparsion in node js script. I have

function zip(fileName) {...}
process.env.TESTING = false;
zip(`${file}_${process.env.TESTING ? 'dev' : 'prod'}.zip`)

But fileName always file_dev.zip regardless of process.env.TESTING value

console.log(process.env.TESTING); // false
console.log(process.env.TESTING ? 'dev' : 'prod'); // always 'dev'

Why value is boolean false but comparsion result always true?

But browser console works as expected

`process.env` will always contain strings. Instead of `false` you have `"false"` (= a string). — marvinhagemeister, Aug 08 '17 at 08:57

kailash yogeshwar · Accepted Answer · 2017-08-08T09:13:00.110

3

  process.env.VARIABLE

Always stores value as string so false will be 'false' and not boolean false.

process.env.VARIABLE === 'false'? 'prod':'dev'

edited Aug 08 '17 at 09:13

answered Aug 08 '17 at 08:57

kailash yogeshwar

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`!!'false'` is also `true`… – deceze Aug 08 '17 at 08:58
then i guess you should check by using == 'false' – kailash yogeshwar Aug 08 '17 at 09:01

score 2 · Answer 2 · answered Aug 08 '17 at 08:57

If this value comes from the environment, won't its value be the string 'false'? Can you confirm with console.log(typeof process.env.TESTING) that it's a boolean?

If it turns out to be a string, you should rewrite the comparison as process.env.TESTING == 'false' ? 'prod' : 'dev'

Node js ternary operator why comparsion goes wrong?

2 Answers2