Analyze javascript original values and Object Reference instances, and analyze javascript instances

Analyze javascript original values and Object Reference instances, and analyze javascript instances

This article describes the original javascript values and object reference methods. Share it with you for your reference. The specific analysis is as follows:

In a word, the original value is unchangeable, and the object reference is variable.

The original values (undefined, null, Boolean, number, and string) in js are essentially different from objects (including arrays and functions. The original value cannot be changed, and no method can change the original value. For a string, all the methods in the string seem to return a modified string, actually, a new string value is returned:

Var str = "hello world"; s. toUpperCase (); s; // remain unchanged

The comparison of the original values is the comparison of values: they only want to wait when their values are equal.

Objects and original values are different. First, they are variable. Second, object comparison is not a comparison of values; and object comparison is a reference comparison: they only want to wait when they reference the same basic object.
To compare two separate objects or arrays, you must compare their attributes or elements, as shown below:

Function equ_arrays (a, B) {if (a. length! = B. lenght) return false; for (var I = 0; I <a. length; I ++) if (a [I]! = B [I]) return false; return true ;}

I hope this article will help you design javascript programs.