To open a ZIP in a browser, pass the file selected by the user directly to JSZip.loadAsync(file). Then find an entry with zip.file(name) and read it as text or bytes with entry.async(...). To create a ZIP for download, add entries and call generateAsync({ type: 'blob' }). These Promise-based APIs make common archive tasks straightforward, but the archive is processed in memory and some ZIP formats are unsupported.
Load JSZip in your browser project
The JSZip homepage lists version 3.10.2 and describes the library as a tool for creating, reading, and editing ZIP files. Check the official JSZip homepage for the current version when setting up a project.
You can install JSZip through npm for a project that uses a bundler, or use its browser distribution files, dist/jszip.js and dist/jszip.min.js. In an unbundled page, the browser build exposes the JSZip global. The official read ZIP guide shows the browser usage pattern.
Open a user-selected ZIP file
A file chosen through an <input type="file"> is a browser File, which inherits from Blob. JSZip accepts Blob input, so you can pass the selected file directly to loadAsync(); a FileReader conversion is not required. The API also accepts ArrayBuffer, Uint8Array, and Promise inputs.
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#1 Best Overall
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
- Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
- Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
- 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.
<input id="zip-input" type="file" accept=".zip,application/zip">
<script>
document.querySelector('#zip-input').addEventListener('change', async (event) => {
const file = event.target.files[0];
if (!file) return;
try {
const zip = await JSZip.loadAsync(file);
console.log(Object.keys(zip.files));
} catch (error) {
console.error('Could not open this ZIP file:', error);
}
});
</script>loadAsync() resolves to a JSZip object containing the archive entries. Listing Object.keys(zip.files) is useful for building a file picker or archive browser; it does not itself extract every entry’s contents. The accepted input types and load behavior are documented in the loadAsync() API reference.
Find and extract a file from the archive
Use zip.file(entryName) to look up a file by its path inside the archive. It returns an entry when found and null otherwise. Call the entry’s async() method to obtain its content as a Promise. Use string for known UTF-8 text, or uint8array for binary data such as images and PDFs.
Rank #2
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
async function readTextFileFromZip(file, entryName) {
const zip = await JSZip.loadAsync(file);
const entry = zip.file(entryName);
if (!entry) throw new Error(`Entry not found: ${entryName}`);
return entry.async('string');
}This helper rejects if the ZIP cannot be loaded or the named entry is absent. The caller should catch that rejection and show an error appropriate to the interface. The available content types and entry lookup behavior are described in the entry async() API reference.
For files already represented as bytes, retrieve a typed array and decide how to consume it in your application:
Rank #3
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
const bytes = await entry.async('uint8array');JSZip’s supported output types can vary by browser; check JSZip.support before relying on Blob, ArrayBuffer, or Uint8Array output in a particular environment. Text returned through async('string') is decoded as UTF-8. For other text encodings, extract bytes and decode them with an appropriate library. ZIP filenames also have encoding complications: JSZip natively supports UTF-8, and its decodeFileName option allows custom filename decoding when an archive uses a different encoding. See the loadAsync() options and async() output options.
Create a ZIP and download it
Add files with .file(name, data) and directories with .folder(name). Then generate a browser Blob and pass it to a download mechanism such as FileSaver’s saveAs.
Rank #4
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
- Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
- Broad Compatible: The usb c to usb adapter widely supports all USB C/ USB A devices like laptops, tablets, cellphones, car chargers, and phone chargers. Such as compatible with MacBook Pro/Air 2023/2022, Thunderbolt 4/3 Devices,Apple MagSafe Watch 9/8/7/SE/Ultra, iPad Pro 2022/2021, Samsung Galaxy S23/S20/S10, and iPhone 17/16/15 Pro. Plug and play
- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
async function makeZipDownload(zip, saveAs) {
const blob = await zip.generateAsync({ type: 'blob' });
saveAs(blob, 'result.zip');
}generateAsync() returns a Promise for the generated representation. Blob is a practical choice for a browser download; supported alternatives include ArrayBuffer and Uint8Array, subject to browser support. See the generateAsync() API reference and the official write ZIP guide.
Choose output compression
Generation supports STORE (no compression) and DEFLATE. DEFLATE accepts a level from 1 through 9: higher compression can trade processing time for a smaller result. Already-compressed entries may be reused, so changing the generation level does not necessarily recompress them. The options are detailed in the generateAsync() documentation.
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- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
What JSZip does not preserve or support
Archive features with limitations
JSZip supports classic ZIP files, but its documentation says encrypted or password-protected archives and multi-volume archives are unsupported. ZIP64 also has limits: very large 64-bit sizes can exceed the range JSZip can safely handle through JavaScript number and bitwise operations. A load or generation failure should be handled as a normal possibility rather than assuming every ZIP is readable. See the JSZip limitations.
Memory use and archive size
Asynchronous processing does not mean streaming with negligible memory use. JSZip’s documentation says async() and generateAsync() hold the full result in memory, although they do not freeze the browser like synchronous processing can. JavaScript strings also use UTF-16, and performance depends on the archive, browser, and device. There is no universal safe archive-size threshold in the documentation; set limits based on your application and test on the devices you support.
Entry paths and round-tripping
Since JSZip 3.8.0, loading sanitizes relative path components in entry names to mitigate zip-slip paths and records the original name in unsafeOriginalName. Do not trust archive-provided paths if your application later writes extracted data to a filesystem or uses names outside the archive object. Also, reading and regenerating a ZIP does not preserve it byte for byte: metadata can be discarded and folder records can be added. These behaviors are covered by the loadAsync() API reference and limitations documentation.
Handle failures in the interface
Both loading and generation are asynchronous and can reject. Catch those errors at the user-interface boundary, distinguish a missing entry from a file that could not be opened, and provide a useful message rather than leaving the user with a silent failure.
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- Show a clear message if the selected file is not a valid or supported ZIP.
- Check whether the requested entry exists before calling its
async()method. - Catch generation errors and keep the user’s source data available so they can retry or choose a smaller selection.
- For large archives, provide progress or a responsive status indicator where appropriate, while recognizing that progress updates do not remove memory constraints.
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