using bitwise OR in javascript to convert to integer

Question

we can do the following to convert:

var a = "129.13"|0,  // becomes 129

var b = 11.12|0; // becomes 11

var c = "112"|0; // becomes 112

This seem to work but not sure if this is a standard JS feature. Does any one have any idea if this is safe to use for converting strings and decimals to integers ?

Answer 1

Yes, it is standard behavior. Bitwise operators only operate on integers, so they convert whatever number they're give to signed 32 bit integer.

This means that the max range is that of signed 32 bit integer minus 1, which is 2147483647.

(Math.pow(2, 32) / 2 - 1)|0; // 2147483647

(Math.pow(2, 32) / 2)|0; // -2147483648 (wrong result)