maskr

maskr

A tiny (156B) utility to compare a string against a template mask.

Demo

Technically, this is still a WIP! See the Roadmap.

Use this module to compare a value against a desired template. Put differently, you can format a string however you'd like.

This is probably most useful for "masking" <input /> values. There are no EventListeners included in this module

Install

$ npm install --save maskr

Usage

const maskr = require('maskr');
const demo = '(___) ___-____';

maskr(demo, '');
//=> { value:'(___) ___-____', cursor:1 }

maskr(demo, '12345678');
//=> { value:'(123) 456-78__', cursor:12 }

maskr(demo, '1234567890');
//=> { value:'[phone]', cursor:14 }

Example <form /> Usage: (demo)

const maskr = require('maskr');
const form = document.getElementById('form');
const inputs = form.querySelectorAll('input');

function setValue(ev) {
  if (ev !== void 0 && ev.type === 'keydown') {
    ev.preventDefault();
    this._value += ev.key;
  }
  const mask = this.getAttribute('data-mask');
  const { value, cursor } = maskr(mask, this._value);
  // set visible value & cursor position
  this.value = value;
  this.setSelectionRange(cursor, cursor);
}

[].forEach.call(inputs, el => {
  if (!el.hasAttribute('data-mask')) return;
  // init internal tracking
  el._value = el.value || '';
  // first-run if has value
  (el.value.length > 0) && setValue.call(el);
  // attach listeners
  el.onfocus = el.onkeydown = setValue.bind(el);
});

API

maskr(mask, input)

mask

Type: string

The template/mask to be used.

input

Type: string

The value string to match against the mask.

Roadmap

• 1.0
  • Recognize _ character only (signifes "any")
  • Find fastest + lightest implementation
• 2.0
  • Recognize _ (any), a (alpha), and 9 (numeric) characters
  • Likely change API/Type definition
  • Add options: showEmpty, custom definitions, ...
• 3.0
  • Use ? for optional masked input
  • TBD

Benchmarks

maskr
  --> 6,415,566 ops/sec ±0.31% (94 runs sampled)

License

MIT © Luke Edwards