<label for="file">

    <img src="data:images/morende.jpg" alt="">

    <span>点击更换头像</span>
</label>

<input type="file" name="file" id="file" accept="image/*" value="" hidden=""/>

$("input[type='file']").change( function(event) {//上传图片
　　console.log(event)
       var file = event.currentTarget.files[0]

        var formFile = new FormData();

        formFile.append("file", file); 

        $.ajax({

            url: ajaxURL+'/currency/istImage',

            type: 'POST',

            data: formFile,

            async: true,

            cache: false,

            contentType: false,

            processData: false,

            dataType:'json',

            success: function(res) {

                console.log(res);

            }

        })

    });

<input type="file" onchange="upload(this)">
<script>

function upload(obj){

var files = obj.files ;

var formData = new FormData();

for(var i = 0;i<files.length;i++){

formData.append("upfile[]", files[i]);

}

$.ajax({

url: "1.php",

type: "POST",

data:formData,

cache:false, //不设置缓存

processData: false, // 不处理数据

contentType: false // 不设置内容类型

});

}

</script>