js实现上传图片功能

话不多说，直接看代码

let inputChoose = document.createElement('input')
inputChoose.setAttribute('type','file')
inputChoose.click()
inputChoose.onchange = function(){
    let file = inputChoose.files[0]
    let index = file.name.lastIndexOf('.')
    let fileText = file.name.substring(index,file.name.length)
    let fileName = fileText.toLowerCase() //文件类型
    if(fileName != '.png' || fileName != '.jpg'){
        alert('系统仅支持 JPG或PNG 格式的图片，请您调整格式后重新上传')
        return                
     }

     let isLt2M = file.size/1024/1024 < 5
     if(!isLt2M){
        alert('图片大小不能超过5M,请重新上传')
        return      
     }

    let formData = new FormData()
    formData.append('file',file)
    formData.append('access_token',Config.TOKEN)   
    ``formData  就是传给上传接口得参数``
 }