Principle and usage analysis of Vue js with statement

The compilation part of vue source code has the following 1 code, which uses with:

export function generate (
 ast: ASTElement | void,
 options: CompilerOptions
): CodegenResult {
 const state = new CodegenState(options)
 const code = ast ? genElement(ast, state) : '_c("div")'
 return {
  render: `with(this){return $[code]}`,
  staticRenderFns: state.staticRenderFns
 }
}

The usage of with under 1 is explained in detail below:

One of the types we commonly use in js is objects:

let obj = {
  a:"aa",
  b:"bb",
  c:"cc"
}

When it comes to an object, we can get the property values in it by using the following methods:

// 1 : 
let a = obj.a
//2 : 
let b = ojb["b"]

To take out every attribute value in the object, we need obj...., which will virtually enter obj many times, so how can we simply get its attribute value?

1. Conventional methods:

var a = obj.a;
var b = obj.b;
var c = obj.c;

2. The method after using with:

with(obj){
  var a = a;
  var b = b;
  var c = c;
}

Here, the values in with parentheses are our public objects, and the following are the values in each object

var qs1 = location.search.substring(1);
var hostname1 = location.hostname;
var url1 = location.href;
 
//  The above lines of code all contain location Object, you can use the with Statement is shortened to the following form 
 
with(location){
  var qs2 = search.substring(1);
  var hostname2 = hostname;
  var url2 = href;
}

As long as it will undoubtedly greatly improve our efficiency.

But everything has advantages and disadvantages, and we have to mention the disadvantages of with:

The with statement is not recommended when developing large applications because of the performance degradation caused by heavy use of the with statement and the difficulty of debugging the code