代码随想录day2

vscode 自定义代码模板

1. select User snippets from Settings on the bottom left corner.
   

2. select a certain language

for example: cpp

3. create your own snippets
   格式如下，防着写

• 第一行"cpp template",模板的名称
• “prefix”,快捷键,在文件中输入cpp,按下tab就会自动填充"body"里的代码。
• ${CURRENT_YEAR} 这个是个变量，当年年份
• $1, $2,$3…是光标的顺序，按TAB键就可以切换为下一个，$0特殊 为光标最后所在地方。
• "description"代码片段描述，随便写写。
  

{
	"cpp template": {
		"prefix": "cpp",
		"body": [
			"/** ",
			" * @Date: ${CURRENT_YEAR} ${CURRENT_MONTH_NAME_SHORT} ${CURRENT_DATE}",
			" * @Time: ${CURRENT_HOUR}:${CURRENT_MINUTE}",
			" * @Author: Chris",
			" * @Desc: ${1:Input the description of this file}",
			"**/"
			"#include ",
			"",
			"using namespace std;",
			"",
			"int main() {",
			"	$0",
			"	return 0;",
			"}",
		],
		"description": "A cpp file template."
	}	
}

4. Usage
   输入cpp，然后按下tab
   

效果如图,光标先跳到desc 这里输入完文件描述，然后按下tab，光标就会跳到主函数里面

Reference

Snippets in Visual Studio Code

Javascript

二维数组初始化

let res = new Array(n).fill(0).map(
        () => new Array(n).fill(0)
    )

为什么要添加fill(0)，而不是直接调用map()?

• The map() method in JavaScript is used to create a new array populated with the results of calling a provided function on every element in the original array. This method is an iterative method, meaning it calls the provided callbackFn function once for each element in the array, constructing a new array from these results. Crucially, callbackFn is invoked only for array indices that have assigned values; it is not invoked for empty slots in sparse arrays

Reference

Array.prototype.map()