What is the usage of with in javascript

Usage of with in javascript: 1. The with statement provides a namespace-style shorthand method for level-by-level object access; 2. A shortcut to repeatedly reference multiple properties in the same object does not need to be repeated. Reference to the object itself.

The operating environment of this tutorial: Windows 7 system, JavaScript version 1.8.5, DELL G3 computer.

Usage of with in javascript:

The original intention of the with statement is to provide a namespace-style shortcut for level-by-level object access. That is, in the specified code area, call the object directly by the node name.

with is usually used as a shortcut to repeatedly reference multiple properties in the same object without repeatedly referencing the object itself.

For example, there is currently an object like this:

var obj = {
a: 1,
b: 2,
c: 3
};

If you want to change the value of each item in obj, the general writing method may be like this:

// 重复写了3次的“obj”
obj.a = 2;
obj.b = 3;
obj.c = 4;

And There will be a simple shortcut by using with writing method

with (obj) {
a = 3;
b = 4;
c = 5;
}

In this code, the with statement is used to associate the obj object, which means that inside the with code block, each variable is first Considered as a local variable, if the local variable has the same name as a property of the obj object, then this local variable will point to the property of the obj object.

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