What is the difference between parseInt(string) and Number(string) in JavaScript? [duplicate]

by 
parseInt("123qwe")

returns 123

Number("123qwe")

returns NaN

In other words parseInt() parses up to the first non-digit and returns whatever it had parsed. Number() wants to convert the entire string into a number, which can also be a float BTW.

EDIT #1: Lucero commented about the radix that can be used along with parseInt(). As far as that is concerned, please see THE DOCTOR’s answer below (I’m not going to copy that here, the doc shall have a fair share of the fame…).

EDIT #2: Regarding use cases: That’s somewhat written between the lines already. Use Number() in cases where you indirectly want to check if the given string completely represents a numeric value, float or integer. parseInt()/parseFloat() aren’t that strict as they just parse along and stop when the numeric value stops (radix!), which makes it useful when you need a numeric value at the front “in case there is one” (note that parseInt("hui") also returns NaN). And the biggest difference is the use of radix that Number() doesn’t know of and parseInt() may indirectly guess from the given string (that can cause weird results sometimes).

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