2.1 KiB
2.1 KiB
js info
预编译
链接：
this 指向
https://www.cnblogs.com/pssp/p/5216085.html
demo1:
function f() {
console.log(aa); // undefined
var aa = 5;
console.log(aa); // 5
}
f();
demo2:
var scope = 'global';
function t() {
console.log(scope); // undefined
var scope = 'local';
console.log(scope); // local
}
t();
console.log(scope); // global
demo3:
console.log(b) //undefined 变量提升
var b =2;
demo4
console.log(foo)
function foo(){
}
var foo =1
作用域
demo1:
function zxxFn () {
zxxs = 2
}
var zxx = 1
console.log(window.zxx) // 1
// console.log(zxxs) 未定义
zxxFn() // 执行后zxxs成为全局变量
console.log(zxxs) // 2
var zxx = 'zxx is a good girl'
function zxxFn () {
console.log(zxx)
var zxx = 'zxx is a great girl'
console.log(zxx)
zxx = 'very good'
console.log(zxx)
}
console.log(zxx)
zxxFn()
console.log(zxx)
// 依次输出 1. zxx is a good girl 2. undefined 3. zxx is a great girl
// 4. very good 5.zxx is a good girl
zxxAge = 'zxx is 18 years old'
function zxxFn () {
console.log(zxxAge)
var zxxAge = 'zxx is 8 years old'
var zxxSub = 'zxx is 25 years old'
console.log(zxxAge) // zxx is 8 years old
// console.log(zxxSub) // zxxSub is not defined
function zxxFnSub () {
var zxxSub = 'zxx is 18 years old'
console.log(zxxSub) // zxx is 18 years old
console.log(zxxAge) // zxxSub is not defined
}
zxxFnSub()
}
zxxFn()
js dom
js dom 初识： https://juejin.cn/post/6907112616221966350
js dom操作 https://juejin.cn/post/6844903593011576845
jq dom操作
作业：
通过在页面上点击button，实现主题切换 主题1：黑底白字 主题2：粉底绿字
五环之歌
点击按钮显示一个五行四列的表格 内容自定义
自定义一个6行的ul列表 点击删除