上传图片在前台预览

document.getElementById(‘file‘).onchange = function(){
        var reader = new FileReader();
        reader.readAsDataURL(this.files[0]);
        reader.onload = function(e) {
            document.getElementById(‘img‘).src = e.target.result;
        }
    }    

function getObjectURL(file) {
        var url = null;
        if (window.createObjectURL != undefined) {
            url = window.createObjectURL(file);
        } else if (window.URL != undefined) {
            url = window.URL.createObjectURL(file);
        } else if (window.webkitURL != undefined) {
            url = window.webkitURL.createObjectURL(file);
        }
        return url;
    }
document.getElementById(‘file‘).onchange = function(){
    document.getElementById(‘img‘).src = getObjectURL(this.files[0]);
}