sqlite/ext/fiddle/index.md

This directory houses a "fiddle"-style application which embeds a Web Assembly (WASM) build of the sqlite3 shell app into an HTML page, effectively running the shell in a client-side browser.

It requires emscripten and that the build environment be set up for emscripten. A mini-HOWTO for setting that up follows...

First, install the Emscripten SDK, as documented here and summarized below for Linux environments:

# Clone the emscripten repository:
$ git clone https://github.com/emscripten-core/emsdk.git
$ cd emsdk

# Download and install the latest SDK tools:
$ ./emsdk install latest

# Make the "latest" SDK "active" for the current user:
$ ./emsdk activate latest

Those parts only need to be run once. The following needs to be run for each shell instance which needs the emcc compiler:

# Activate PATH and other environment variables in the current terminal:
$ source ./emsdk_env.sh

$ which emcc
/path/to/emsdk/upstream/emscripten/emcc

That env script needs to be sourced for building this application from the top of the sqlite3 build tree:

$ make fiddle

Or:

$ cd ext/fiddle
$ make

That will generate the fiddle application under ext/fiddle, as fiddle.html. That application cannot, due to XMLHttpRequest security limitations, run if the HTML file is opened directly in the browser (i.e. if it is opened using a file:// URL), so it needs to be served via an HTTP server. For example, using althttpd:

$ cd ext/fiddle
$ althttpd -debug 1 -jail 0 -port 9090 -root .

Then browse to http://localhost:9090/fiddle.html.

Note that when serving this app via althttpd, it must be a version from 2022-05-17 or newer so that it recognizes the .wasm file extension and responds with the mimetype application/wasm, as the wasm loader is pedantic about that detail.