使用Javascript檢查本地磁盤上是否存在.htm文件

Question

我如何檢查是否一個.htm文件中使用了JavaScript的本地磁盤上存在.htm包含Javascript代碼文件（從網絡服務器並不）本地加載？

Answer 1

該解決方案適用於大多數版本的IE和FF。 從本地磁盤運行時，在Chrome上不起作用。

我在同步模式下使用XHR和舊的IE ActiveX控件。 您可以輕松地將其轉換為使用onreadystatechange回調運行異步。

在您自己的Javascript代碼中，只需調用IsDocumentAvailable（“ otherfile.htm”）即可進行設置。

    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;
    }

Answer 2

本文可能會有所幫助： http : //www.c-point.com/JavaScript/articles/file_access_with_JavaScript.htm

而這： 使用javascript進行本地文件訪問

Answer 3

假設htm文件位於同一域中，則可以執行以下操作：

function UrlExists(url) {
  var http = new XMLHttpRequest();
  http.open('HEAD', url, false);
  http.send();
  return http.status!=404;
}

由於域安全性限制，這在某些瀏覽器（例如Chrome）上的本地文件系統上將不起作用。