Converting string to number - parseInt() vs Number();

Question

Why in this situation when i want to convert string to number parseInt() works but Number() not?

parseInt(this.element.style.left) << it works
Number(this.element.style.left) << it doesn't, there is NaN

Answer 1

With parseInt:

If parseInt encounters a character that is not a numeral in the specified radix, it ignores it and all succeeding characters and returns the integer value parsed up to that point. parseInt truncates numbers to integer values. Leading and trailing spaces are allowed.

In contrast, Number tries to parse the entire argument as a number.

With style.left ending in px, for example, parseInt('12px') works because the px can just be ignored by the parseInt. But Number('12px') doesn't work because all the characters of the '12px' cannot be interpreted as a number.

parseInt skips invalid characters (and stops parsing there), evaluating to what's been parsed so far.

Number fails to parse at all when there are any invalid characters anywhere.