Install JS kernel on Chrome:
1. Download JS kernel for Chrome
2. Open the extension setting page (chrome://extensions).
3. Drag and drop the .crx file into Chrome browser to install the packed app.

Install JS kernel on Firefox:
1. Download JS kernel for Firefox
2. Extract the contents of the zip file.
3. Open the extension debugging page (about:debugging#addons).
4. Click "Load Temporary Add-on" to install the packed app by selecting the manifest.json file.

Install JS kernel on Edge:
1. Download JS kernel for Edge
2. Extract the contents of the zip file.
3. Open "about:flags" and tick "Enable Extension Developer Features" box.
4. Click the "..." button at the top right of the browser.
5. Click the "Extensions" item.
6. Click the "Load Extension" buttion and select the directory you saved the zip file's content to.