使用Javascript检查本地磁盘上是否存在.htm文件

Question

.htm当.htm本地加载包含Javascript代码的文件(而不是从Web服务器)时,如何使用Javascript 检查本地磁盘上是否存在文件？

Answer 1

此解决方案适用于大多数IE和FF版本.从本地磁盘运行时,无法在Chrome上运行.

我在同步模式下使用XHR和旧的IE ActiveX控件.您可以使用onreadystatechange回调轻松地将其转换为运行异步.

在您自己的Javascript代码中,只需调用IsDocumentAvailable("otherfile.htm")即可设置.

    function IsDocumentAvailable(url) {

        var fSuccess = false;
        var client = null;

        // XHR is supported by most browsers.
        // IE 9 supports it (maybe IE8 and earlier) off webserver
        // IE running pages off of disk disallows XHR unless security zones are set appropriately. Throws a security exception.
        // Workaround is to use old ActiveX control on IE (especially for older versions of IE that don't support XHR)

        // FireFox 4 supports XHR (and likely v3 as well) on web and from local disk

        // Works on Chrome, but Chrome doesn't seem to allow XHR from local disk. (Throws a security exception) No workaround known.

        try {
            client = new XMLHttpRequest();
            client.open("GET", url, false);
            client.send();
        }
        catch (err) {
            client = null;
        }

        // Try the ActiveX control if available
        if (client === null) {
            try {
                client = new ActiveXObject("Microsoft.XMLHTTP");
                client.open("GET", url, false);
                client.send();
            }
            catch (err) {
                // Giving up, nothing we can do
                client = null;
            }
        }

        fSuccess = Boolean(client && client.responseText);

        return fSuccess;
    }