（一）方法一：直接在script标签中提前定义，仅适用于该html文件！

 let add = function(a,b){
 	return a + b;
 };
 console.log(add(20,300));
 
 const { ['log']:C } = console;
 C(add(20,300));

（二）方法二：按tab键快速生成console.log，且光标在()内部,再次按tab键光标自动跳转到下一行！
1、打开vscode编辑器，选择文件->首选项->用户片段，输入javascript.json并按下enter进入。
初次使用我们会发现一段被注释的代码如下：

{
	// Place your snippets for javascript here. Each snippet is defined under a snippet name and has a prefix, body and 
	// description. The prefix is what is used to trigger the snippet and the body will be expanded and inserted. Possible variables are:
	// $1, $2 for tab stops, $0 for the final cursor position, and ${1:label}, ${2:another} for placeholders. Placeholders with the 
	// same ids are connected.
	// Example:
	// "Print to console": {
	// 	"prefix": "log",
	// 	"body": [
	// 		"console.log('$1');",
	// 		"$2"
	// 	],
	// 	"description": "Log output to console"
	// }
}

2、解除Example以下的区间代码如下，其中部分参数意义如下：
①prefix:代码快捷键的入口,在这里我们根据个人习惯进行设置即可，如我设置的cl,那么配合tab健就可以直接生成console.log；
②body表示代码主体：
$1表示生成代码快速生成后后光标首次出现的位置
$2写在"console.log('$1');"下面,表示在快速生成console.log()后,代码后会空出一行,并且再次按tab键时,光标会跳转到$2（空出的一行）的位置

{
	// Place your snippets for javascript here. Each snippet is defined under a snippet name and has a prefix, body and 
	// description. The prefix is what is used to trigger the snippet and the body will be expanded and inserted. Possible variables are:
	// $1, $2 for tab stops, $0 for the final cursor position, and ${1:label}, ${2:another} for placeholders. Placeholders with the 
	// same ids are connected.
	// Example:
	"Print to console": {
		"prefix": "cl",
		"body": [
			"console.log('$1');",
			"$2"
		],
		"description": "Log output to console"
	}
}