Jesse Clark’s Blog

Conditional Live-Reload with Metalsmith CLI

by Jesse Clark
Last edited

Metalsmith is a popular static site generator.

The metalsmith command-line interface allows a build process to be defined by a single JSON file. If you want to vary the build process in different situations, you need to write a script that duplicates much of the logic of the CLI. It's possible to avoid duplication by requiring the CLI binary from another script. This gives us an opportunity to modify the config with conditional or non-serializable data:

var config = require('./metalsmith.json');
// provide a formatting function for use in templates
config.metadata.formatDate = function(date, format) {
    return require("moment")(date).format(format || "MMMM Do, YYYY");
// only enable live-reloading when requested
if (process.env.AUTO_RELOAD) {
    config.plugins['metalsmith-watch'] = { livereload: 35729 };
    config.metadata.customHTML = '<script src="http://localhost:35729/livereload.js?snipver=1"></script>');

// run the standard CLI

This lets us use the same general config for both batch processing and live-reloading, which would otherwise be incompatible.

node build.js                  # terminates after building
AUTO_RELOAD=1 node build.js    # keeps running until killed