If you're looking to get hired as a front-end dev at any level above entry-level, you definitely need to know what a closure is - not just for its utility, but

If you're looking to get hired as a front-end dev at any level above entry-level, you definitely need to know what a closure is - not just for its utility, but because it can cause nasty bugs when you implement it unknowingly. If I were hiring a mid-level or senior-level front-end engineer and they do not know what a closure is, that'd be a red flag for unfamiliarity with a core language feature. It's on par with not knowing what a decorator is in Python, or reflection in Java.