Javascript有一个文件系统API。如果你可以让这个功能只在Chrome中工作，一个好的起点是:http://www.html5rocks.com/en/tutorials/file/filesystem/。

对于Chrome和Firefox，我一直使用纯JavaScript方法。

(我的应用程序不能使用Blob.js这样的包，因为它是由一个特殊的引擎提供的:一个DSP和一个WWWeb服务器，几乎没有空间容纳任何东西。)

function FileSave(sourceText, fileIdentity) {
    var workElement = document.createElement("a");
    if ('download' in workElement) {
        workElement.href = "data:" + 'text/plain' + "charset=utf-8," + escape(sourceText);
        workElement.setAttribute("download", fileIdentity);
        document.body.appendChild(workElement);
        var eventMouse = document.createEvent("MouseEvents");
        eventMouse.initMouseEvent("click", true, false, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);
        workElement.dispatchEvent(eventMouse);
        document.body.removeChild(workElement);
    } else throw 'File saving not supported for this browser';
}

注释、警告和模棱两可的词语:

I have had success with this code in both Chrome and Firefox clients running in Linux (Maipo) and Windows (7 and 10) environments. However, if sourceText is larger than a MB, Chrome sometimes (only sometimes) gets stuck in its own download without any failure indication; Firefox, so far, has not exhibited this behavior. The cause might be some blob limitation in Chrome. Frankly, I just don't know; if anybody has any ideas how to correct (or at least detect), please post. If the download anomaly occurs, when the Chrome browser is closed, it generates a diagnostic such as This code is not compatible with Edge or Internet Explorer; I have not tried Opera or Safari.

function SaveBlobAs(blob, file_name) {
    if (typeof navigator.msSaveBlob == "function")
        return navigator.msSaveBlob(blob, file_name);

    var saver = document.createElementNS("http://www.w3.org/1999/xhtml", "a");
    var blobURL = saver.href = URL.createObjectURL(blob), 
        body = document.body;

    saver.download = file_name;

    body.appendChild(saver);
    saver.dispatchEvent(new MouseEvent("click"));
    body.removeChild(saver);
    URL.revokeObjectURL(blobURL);
}

Awesomeness01对代码的一个非常小的改进(不需要锚标签)，增加了trueimage的建议(支持IE):

// Function to download data to a file
function download(data, filename, type) {
    var file = new Blob([data], {type: type});
    if (window.navigator.msSaveOrOpenBlob) // IE10+
        window.navigator.msSaveOrOpenBlob(file, filename);
    else { // Others
        var a = document.createElement("a"),
                url = URL.createObjectURL(file);
        a.href = url;
        a.download = filename;
        document.body.appendChild(a);
        a.click();
        setTimeout(function() {
            document.body.removeChild(a);
            window.URL.revokeObjectURL(url);  
        }, 0); 
    }
}

测试在Chrome, FireFox和IE10中正常工作。

在Safari中，数据在一个新选项卡中打开，必须手动保存该文件。

对于最新的浏览器，如Chrome，你可以使用本教程中的文件API:

window.requestFileSystem  = window.requestFileSystem || window.webkitRequestFileSystem;
window.requestFileSystem(window.PERSISTENT, 5*1024*1024 /*5MB*/, saveFile, errorHandler);

你不能单纯地在Javascript中做到这一点。由于安全原因，Javascript在浏览器上运行还没有足够的权限(已经提出了建议)。

相反，我建议使用downadify:

一个微小的javascript + Flash库，可以创建和下载文本文件，无需服务器交互。

您可以在这里看到一个简单的演示，其中提供内容并测试保存/取消/错误处理功能。