如何在内存中创建文件供用户下载，而不是通过服务器下载？

If the file contains text data, a technique I use is to put the text into a textarea element and have the user select it (click in textarea then ctrl-A) then copy followed by a paste to a text editor.

This below function worked.

 private createDownloadableCsvFile(fileName, content) {
   let link = document.createElement("a");
   link.download = fileName;
   link.href = `data:application/octet-stream,${content}`;
   return link;
 }

We can use the URL api, in particular URL.createObjectURL(), and the Blob api to encode and download pretty much anything.

document.body.innerHTML += 
`<a id="download" download="PATTERN.json" href="${URL.createObjectURL(new Blob([JSON.stringify("HELLO WORLD", null, 2)]))}"> Click me</a>`
download.click()
download.outerHTML = ""

Bonus! Download any cyclic objects, avoid the errors:

TypeError: cyclic object value (Firefox) TypeError: Converting

circular structure to JSON (Chrome and Opera) TypeError: Circular

reference in value argument not supported (Edge)

Using https://github.com/douglascrockford/JSON-js/blob/master/cycle.js

/* JSON.decycle */
if(typeof JSON.decycle!=="function"){JSON.decycle=function decycle(object,replacer){"use strict";var objects=new WeakMap();return(function derez(value,path){var old_path;var nu;if(replacer!==undefined){value=replacer(value)}
if(typeof value==="object"&&value!==null&&!(value instanceof Boolean)&&!(value instanceof Date)&&!(value instanceof Number)&&!(value instanceof RegExp)&&!(value instanceof String)){old_path=objects.get(value);if(old_path!==undefined){return{$ref:old_path}}
objects.set(value,path);if(Array.isArray(value)){nu=[];value.forEach(function(element,i){nu[i]=derez(element,path+"["+i+"]")})}else{nu={};Object.keys(value).forEach(function(name){nu[name]=derez(value[name],path+"["+JSON.stringify(name)+"]")})}
return nu}
return value}(object,"$"))}}


document.body.innerHTML += 
`<a id="download" download="PATTERN.json" href="${URL.createObjectURL(new Blob([JSON.stringify(JSON.decycle(document), null, 2)]))}"></a>`
download.click()

As of April 2014, FileSytem APIs may not be standardized in W3C. Anyone looking at the solution with blob should thread with caution, I guess.

HTML5 rocks heads up

W3C Mailing List on FileSytem API

在IE10上有效的解决方案：（我需要一个csv文件，但足以将类型和文件名更改为txt）

var csvContent=data; //here we load our csv data 
var blob = new Blob([csvContent],{
    type: "text/csv;charset=utf-8;"
});

navigator.msSaveBlob(blob, "filename.csv")

此解决方案直接从tiddlywiki（tiddlywiki.com）github存储库中提取。我在几乎所有浏览器中都使用过tiddlywiki，它的工作原理很像：

function(filename,text){
    // Set up the link
    var link = document.createElement("a");
    link.setAttribute("target","_blank");
    if(Blob !== undefined) {
        var blob = new Blob([text], {type: "text/plain"});
        link.setAttribute("href", URL.createObjectURL(blob));
    } else {
        link.setAttribute("href","data:text/plain," + encodeURIComponent(text));
    }
    link.setAttribute("download",filename);
    document.body.appendChild(link);
    link.click();
    document.body.removeChild(link);
}

Github仓库： 下载保护程序模块

我很高兴使用FileSaver.js。它的兼容性非常好（IE10 +和其他所有功能），并且使用非常简单：

var blob = new Blob(["some text"], {
    type: "text/plain;charset=utf-8;",
});
saveAs(blob, "thing.txt");

以下方法适用于IE11 +，Firefox 25+和Chrome 30+：

<a id="export" class="myButton" download="" href="#">export</a>
<script>
    function createDownloadLink(anchorSelector, str, fileName){
        if(window.navigator.msSaveOrOpenBlob) {
            var fileData = [str];
            blobObject = new Blob(fileData);
            $(anchorSelector).click(function(){
                window.navigator.msSaveOrOpenBlob(blobObject, fileName);
            });
        } else {
            var url = "data:text/plain;charset=utf-8," + encodeURIComponent(str);
            $(anchorSelector).attr("download", fileName);               
            $(anchorSelector).attr("href", url);
        }
    }

    $(function () {
        var str = "hi,file";
        createDownloadLink("#export",str,"file.txt");
    });

</script>

在操作中查看此内容：http : //jsfiddle.net/Kg7eA/

Firefox和Chrome支持导航的数据URI，这使我们可以通过导航到数据URI来创建文件，而IE出于安全目的不支持它。

另一方面，IE具有用于保存Blob的API，可用于创建和下载文件。

您可以使用数据URI。浏览器支持各不相同；参见维基百科。例：

<a href="data:application/octet-stream;charset=utf-16le;base64,//5mAG8AbwAgAGIAYQByAAoA">text file</a>

八位字节流将强制进行下载提示。否则，它可能会在浏览器中打开。

对于CSV，您可以使用：

<a href="data:application/octet-stream,field1%2Cfield2%0Afoo%2Cbar%0Agoo%2Cgai%0A">CSV Octet</a>

尝试jsFiddle演示。