<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title></title>
<style>
</style>
</head>
<body>
<input type="file" id="file" />
<input type="submit" id="btn"/>
<div id="result">
</div>
<script>
var oFlie = document.getElementById("file")
var oBtn = document.getElementById("btn")
var oRes = document.getElementById("result")
var oImg = document.getElementsByTagName("img")
var onOff = true
oBtn.onclick = function(){
var oType = oFlie.files[0].type
var fs = oFlie.files[0]
// console.log(oType)
var pattern = /^(image)\/\w+/
if(!pattern.test(oType)){
oRes.innerHTML = "不可以上传"
}
var reader = new FileReader()
// console.log(reader)
reader.readAsDataURL(fs)
// console.log(reader)
reader.onload = function(){
// console.log("完成了")
console.log(onOff,"1111")
if(onOff){
var oNode = document.createElement("img")
oNode.src = this.result
oNode.width = 100
oNode.height = 100
oRes.appendChild(oNode)
}else {
alert("ss")
}
// console.log(this.result)
// console.log(oImg[0].src==this.result)
for (var i=0;i<oImg.length;i++) {
if(oImg[i].src==this.result){
onOff = false
}
}
console.log(onOff)
}
}
</script>
</body>
</html>
使用: