Performance Optimization of type conversion in javascript

1. convert a number into a String and apply "" + 1. Although it looks ugly, the efficiency is actually the highest. In terms of performance: ("" +)> String ()>. toString ()> new String (): internal operations that can be used during compilation are faster than those used during running. String () is an internal function, so the speed is very fast, and. toString () is used to query functions in the prototype, so the speed is inferior. new String () is used to return an exact copy.

2. converting a floating point to an integer is more prone to errors. Many people prefer parseInt (). In fact, parseInt () is used to convert a string to a number, rather than converting between a floating point and an integer, we should use Math. floor () or Math. round (). In addition, Math is an internal object, which is different from the problem in Object Search in section 2. Therefore, Math. floor () does not actually have many query methods and call times, and the speed is the fastest.

3. for custom objects, if the toString () method is defined for type conversion, we recommend that you explicitly call toString (), because after all the possibilities of internal operations are attempted, will try to convert the toString () method of the object.