【前端】語法學習
阿新 • • 發佈:2022-04-11
<script> // var 定義變數 { var a = 10 var b = "zhangsan" } console.log(a , b) var a = 20 var b = 30 console.log(a , b) a = 40 b = 50 console.log(a , b) // let 定義變數 let c = 60 let d = "lisi" // let c = 70 -- let 定義的變數不能被二次定義,但是可以二次賦值 c = 70 d = 80 console.log(c , d) { c = 80 d = 'wangwu' console.log("內部:" + c , d) let e = 1 let f = 2 } console.log("外部:" + c , d) // console.log(e , f) -- 不能被訪問 // 物件 var user = {name:"zhangsan",age:20} console.log(user) // 常量 const const name = "wangwu" const age = 23 // 常規語法 user = {name:name,age:age} console.log(user.name + "---" + user.age) // es6語法 user = {name,age} console.log(user.name + "***" + user.age) var dog = {name:"xiaobai",age:3,sex:1} var cat = {name:"xiaohei",age:2,email:"[email protected]"} // 合併物件、修改屬性 var merge = {...dog} console.log(merge) var merge = {...cat} console.log(merge) var merge = {...dog,...cat} console.log(merge) var merge = {...cat,...dog} console.log(merge) var merge = {...dog,name:"xiaohuang"} console.log(merge) // 方法 var person = { name:"zhangsan", age:20, eat(name){ alert(name + "吃飯!") }, sleep(){ alert(this.name + "睡覺覺!") } } person.eat("zhaoliu") person.sleep() // 箭頭函式: 引數 => 函式體 var f1 = num => num alert(f1("hello world")) var f2 = (a,b) => a + b alert(f2(1,2)) alert(f2("hello","world")) </script>