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<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title></head><body><script>// 变量 命名规则，遵循驼峰式，或蛇形式let num = 12; //值类型// 常量 一般字母全大写const P = 3.14;// 数据类型let str = "Hello"; //字符串let bool = true; //布尔 (以及Null,Undefined类型)function printStr(){console.log("值类型变量num:"+num+"常量P:"+P+"字符串类型str:"+str+"布尔类型bool:"+bool);}// 匿名函数let func = function (){console.log("值类型变量num:"+num+"常量P:"+P+"字符串类型str:"+str+"布尔类型bool:"+bool);}// 箭头函数转化let funct = () => console.log("值类型变量num:"+num+"常量P:"+P+"字符串类型str:"+str+"布尔类型bool:"+bool);function returnData(){return '返回值';}function returnData(...arr){let num = 0;for(let i = 0; i < arr.length; i ++){num += arr[i];}return num;}func();funct();returnData();let arr = [1,2,3,4,5,6]console.log(returnData(...arr)) //归并，若参数为数组，必须加...，否则无法展开</script></body></html>