图片上传即时显示javascript代码

时间：2021-06-25 23:41:32

这是基于javascript的一种图片上传即时显示方法，测试结果IE6和火狐浏览器可以正常使用。google浏览器不兼容。

这种方法兼容性比较差，仅供参考，建议使用ajax方法来即时显示图片。

1.首先是javascript代码

/**

 * 图片上传即时显示javascript

 */

var allowExt = [ 'jpg', 'gif', 'bmp', 'png', 'jpeg' ];

var preivew = function(file, container) {

    try {

        var pic = new Picture(file, container);

    } catch (e) {

        alert(e);

    }

};

// 缩略图类定义

var Picture = function(file, container) {

    var height = 0, widht = 0, ext = '', size = 0, name = '', path = '';

    var self = this;

    if (file) {

        name = file.value;

        if (window.navigator.userAgent.indexOf("MSIE") >= 1) {

            file.select();

            path = document.selection.createRange().text;

        } else if (window.navigator.userAgent.indexOf("Firefox") >= 1) {

            if (file.files) {

                path = window.URL.createObjectURL(file.files[0]);

            } else {

                path = file.value;

            }

        }

    } else {

        throw "bad file";

    }

    ext = name.substr(name.lastIndexOf("."), name.length);

    if (container.tagName.toLowerCase() != 'img') {

        throw "container is not a valid img label";

        container.visibility = 'hidden';

    }

    container.src = path;

    container.alt = name;

    container.style.visibility = 'visible';

    height = container.height;

    widht = container.widht;

    size = container.fileSize;

    this.get = function(name) {

        return self[name];

    };

    this.isValid = function() {

        if (allowExt.indexOf(self.ext) !== -1) {

            throw 'the ext is not allowed to upload';

            return false;

        }

    };

};

2.html代码，主要在于onchange方法调用上面的javascript方法，然后是一个用来显示图片的img标签

<body>

    <input name="image"nchange="preivew(this,document.getElementById('img'));"/>

    <img id="img" style="visibility:hidden" height="150px" width="500px">

</body>

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