esbuild.js

import esbuild from 'esbuild'

// Basic options
const options = {

    // Entry points and the path to the final bundle
    entryPoints: ['src/index.ts'],
    outdir: 'dist',

    // Whether to bundle together, minify and add a source map
    bundle: true,
    minify: true,
    sourcemap: true,

    // A target environment (esbuild doesn’t support this option specified in tsconfig.json)
    target: 'es6',

    // Log level is specified in order to print basic information even when launched as an npm script from package.json
    logLevel: 'info'
}

// Different types of builds
const configs = {

    // The default one. Builds right away
    'build': () => esbuild.build(options),

    // The watching one. Sets the context and starts the watching process
    'watch': () => esbuild.context(options).then(r => r.watch())
}

/* 
Run the config. A command of the type `node esbuild.js watch` should be used. The third element of the command will be treated as a config name
*/
await configs[process.argv[2]]()
    .catch(e => {
        console.error(e)
        process.exit(1)
    })