How do I work around JavaScript's parseInt octal behavior?

Question

Try executing the following in JavaScript:

parseInt(\'01\'); //equals 1
parseInt(\'02\'); //equals 2
parseInt(\'03\'); //equals 3
parseInt(\'04\'); //equals          


        

Answer 1

If you know your value will be in the signed 32 bit integer range, then ~~x will do the correct thing in all scenarios.

~~"08" === 8
~~"foobar" === 0
~~(1.99) === 1
~~(-1.99)  === -1

If you look up binary not (~), the spec requires a "ToInt32" conversion for the argument which does the obvious conversion to an Int32 and is specified to coerce NaN values to zero.

Yes, this is incredibly hackish but is so convenient...