es6简单基础：
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1" />
<title>1</title>
<style type="text/css">
*{margin: 0;padding: 0;}
</style>
<script type="text/javascript">
/*
let const 只在申明的块中有效
const申明的变量，类型不能变 var可以变类型
const申明常量用大写
*/
var a=1;
{
let a=3;
console.log(a);
const ARR=[1,2];
ARR.push(3);
console.log(ARR);
// ARR=10;//此处会报错
}
console.log(a);
{
let a=(x)=>(x*2);
console.log(a(10));
}
{
let a=(x,y=10)=>(x+y);
console.log(a(2),a(2,3));
}
{
let a=(x)=>function(){
return 2;
}();
console.log(a(1));
}
{
let a=[1,2,3];
let b=a.map(f=>{
return f+'s';
});
console.log(b);
}
{
function Person(){
this.age=0;
this.addAge=()=>(this.age++);
}
let p=new Person();
p.addAge();
console.log(p.age);
} //创建canvas及画图
let newCanvas=()=>{
let c=document.createElement("canvas");
c.width=window.screen.width;
c.height=window.screen.height;
let d=c.getContext("2d");
d.fillStyle="red";
d.fillRect(10,10,100,100);
return c;
};
//canvas保存为图片
let canvasToImg=(canvas)=>{
let image=new Image();
image.src=canvas.toDataURL('image/png');
return image;
}; window.onload=()=>{
//写出canvas图片
document.body.appendChild(canvasToImg(newCanvas()));
}
</script>
</head>
<body> </body>
</html>
1.html
预览本地文件：
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1" />
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title>预览本地文件</title>
<style type="text/css">
video{
background-color: #000;
}
</style>
<script type="text/javascript">
/**
* 从 file 域获取 本地图片 url
*/
function getFileUrl(sourceId) {
var url;
if (navigator.userAgent.indexOf("MSIE")>=1) { // IE
url = document.getElementById(sourceId).value;
} else if(navigator.userAgent.indexOf("Firefox")>0) { // Firefox
url = window.URL.createObjectURL(document.getElementById(sourceId).files.item(0));
} else if(navigator.userAgent.indexOf("Chrome")>0) { // Chrome
url = window.URL.createObjectURL(document.getElementById(sourceId).files.item(0));
}
return url;
} /**
* 将本地图片 显示到浏览器上
*/
function preImg(sourceId, targetId){
var url = getFileUrl(sourceId);
console.log(sourceId,targetId);
var imgPre = document.getElementById(targetId);
imgPre.src = url;
}
</script>
</head>
<body>
<form action="">
<input type="file" name="imgOne" id="imgOne" onchange="preImg(this.id,'imgPre');" />
<!-- <img id="imgPre" src="" width="300px" height="300px" style="display: block;" /> -->
<video id="imgPre" width="300px" height="300px" controls="controls" style="display: block;"></video>
</form>
</body>
</html>
2.html