@danielkalen/simplybind/benchmarks/src/bower_components/plastiq/sync.js

Magically simple, framework-less one-way/two-way data binding for frontend/backend in ~5kb.

var plastiq = require('.');
var h = plastiq.html;

module.exports = function () {
  var refresh;
  var throttle;

  var promise, awaitingPromise, lastTime, lastValue, timeout;

  var currentValue;
  var currentFn;

  function callFn() {
    var self = this;

    if (promise) {
      if (!awaitingPromise) {
        promise.then(function () {
          promise = undefined;
          awaitingPromise = undefined;
          sync();
        });

        awaitingPromise = true;
      }
    } else {
      var result = currentFn(currentValue);
      if (result && typeof result.then === 'function') {
        promise = result;
        promise.then(refresh);
      }
      valueChanged();
      lastTime = Date.now();
    }
  }


  function valueHasChanged() {
    return lastValue !== normalisedValue(currentValue);
  }

  function valueChanged() {
    lastValue = normalisedValue(currentValue);
  }

  function sync() {
    var self = this;
    var now = Date.now();

    if (valueHasChanged()) {
      if (!lastTime || (lastTime + throttle < now)) {
        callFn();
      } else if (!timeout) {
        var timeoutDuration = lastTime - now + throttle;
        timeout = setTimeout(function () {
          timeout = undefined;
          callFn();
        }, timeoutDuration);
      }
    }
  }

  return function (value, options, fn) {
    if (typeof options === 'function') {
      fn = options;
      options = undefined;
    }

    refresh = h.refresh;
    throttle = options && options.hasOwnProperty('throttle') && options.throttle !== undefined? options.throttle: 0;

    currentValue = value;
    currentFn = fn;

    sync();
  }
};

function normalisedValue(value) {
  return value.constructor === Object || value instanceof Array
    ? JSON.stringify(value)
    : value;
}