How Can I Unzip Files Asynchronously in a Web Browser Using JavaScript?

Unzipping Files Asynchronously in a Web Browser

Unzipping Zipped Files for Display in a Web Browser

To display OpenOffice files (.odt and .odp) in a web browser, one needs to unzip them first. While inflate.js may not suffice for this task, there exists a robust JavaScript solution to unzip ZIP files asynchronously.

JavaScript Unzipper

A JavaScript unzipper has been developed, incorporating elements from Andy G.P. Na's binary file reader and Notmasteryet's RFC1951 inflate logic. The ZipFile class handles the core functionality.

Implementation in JavaScript

The following JavaScript code demonstrates the usage of the unzipper:

// Instantiate a ZipFile and provide a callback for when the ZIP is read.
zipFile = new ZipFile(url, doneReading);

// The doneReading callback is triggered when the ZIP is read and handles the extraction of entries.
function doneReading(zip) {
    extractEntries(zip);
}

// Extract entries from the ZIP file.
function extractEntries(zip) {
    for (var i = 0; i < zip.entries.length; i++) {
        var entry = zip.entries[i];

        // Create an entry info div.
        var entryInfo = "<h4><a>" + entry.name + "</a></h4>\n<div>";

        // Create a unique ID for the accordion panel and inject the extracted content into it.
        var randomId = "id-" + Math.floor((Math.random() * 1000000000));
        entryInfo += "<span class='inputDiv'><h4>Content:</h4><span id='" + randomId +
            "'></span></span></div>\n";
        $("#report").append(entryInfo);

        // Asynchronously extract the entry and pass a callback.
        entry.extract(extractCb(randomId));
    }
}

// Extract callback function to add the extracted content to an accordion on the page.
function extractCb(id) {
    return (function(entryName, entryText){
        var content = entryText.replace(new RegExp( "\n", "g" ), "<br/>");
        $("#"+id).html(content);
        $('#report').accordion('destroy');
        $('#report').accordion({collapsible:true, active:false});
    });
}

Limitations

While the JavaScript unzipper fulfills its purpose, it faces certain limitations:

• Performance: Decompression can be slow compared to compiled programs, especially with large ZIP files.
• Memory Usage: The unzipper reads the entire ZIP into memory, which can strain system resources with large files.
• Limited Functionality: It does not support all ZIP features, such as encryption, Zip64, and UTF-8 encoded filenames.

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