Javascript, why treated as octal

Question

I\'m passing as parameter an id to a javascript function, because it comes from UI, it\'s left zero padded. but it seems to have (maybe) \"strange\" behaviour?

Answer 1

If number came from server as zero padded string then use +"0000022115"

console.log(+"0000022115")

if (021 < 019) console.log('Paradox');

JS treat zero padded numbers like octal only if they are valid octal - if not then it treat it as decimal. To not allow paradox 'use strict' mode

'use strict'

if (021 < 019) console.log('Paradox');