microtask-debounce.js

// Console.log alias
const l   = (...args)   => console.log(...args)

// Reject promise with custom error alias
const err = (rej, type) => rej(new Error(type))

// SetTimeout alias
const STO = (fn, ms) => setTimeout(fn, ms)

// new Promise alias
const mkProm = function(func, ...args) { return new Promise(func.bind(this, ...args)) }

class Test {
  // timeout ref and amount of time to deflect calls in ms
  constructor () { Object.assign(this, {}, { to: null, dt: 1000 }) }
  run (query, env={}) {
    // Create a promise
    return mkProm((res, rej) => {
      // Track local ref for timeout
      const to = this.to = STO(
        // Compare local ref 
        _ => to === this.to
          // If ref is same as what we originally stored then resolve
          ? res([query])
          // If ref is not the same then reject the call
          : err(rej, 'Debounced')
        , this.dt
      )
    })
    .then(results => l(results)        )
    .catch(error  => l('Script failed'))
  }
}

// Try to call the run fn multiple times in succession
const tester = new Test()
l(tester.run('a'));
l(tester.run('a'));
l(tester.run('b'));

program-output.txt

> node microtask-debounce.js

Promise { <pending> }
Promise { <pending> }
Promise { <pending> }
[ 'b' ]
Script failed
Script failed