mercury/examples/todomvc/lib/raf-listen.js

A truly modular frontend framework

'use strict';

var raf = require('raf');

module.exports = rafListen;

function rafListen(observ, fn) {
    var sending = false;
    var currValue;

    return observ(onvalue);

    function onvalue(value) {
        currValue = value;
        if (sending) {
            return;
        }

        sending = true;
        raf(send);
    }

    function send() {
        var oldValue = currValue;
        fn(currValue);
        sending = false;

        if (oldValue !== currValue) {
            sending = true;
            raf(send);
        }
    }
}