fromEventPattern

• 语法：

Rx.Observable.fromEventPattern(addHandler, [removeHandler], [selector])

• 功能: 通过使用addHandler和removeHandler函数添加和删除处理程序。 当输出Observable被订阅时，addHandler被调用，并且当订阅被取消订阅时调用removeHandler。

eg:

function addClickHandler(handler) {
  document.addEventListener('click', handler);
}

function removeClickHandler(handler) {
  document.removeEventListener('click', handler);
}

var clicks = Rx.Observable.fromEventPattern(
  addClickHandler,
  removeClickHandler
);
clicks.subscribe(x => console.log(x));

f-eg

//jQuery
var input = $('#input');

var source = Rx.Observable.fromEventPattern(
    function add (h) {
        input.bind('click', h);
    },
    function remove (h) {
        input.unbind('click', h);
    }
);

var subscription = source.subscribe(
    function (x) {
        console.log('Next: Clicked!');
    },
    function (err) {
        console.log('Error: ' + err);   
    },
    function () {
        console.log('Completed');   
    });

input.trigger('click');

// => Next: Clicked!`