timers-browserify

1 该插件封装了原生的定时器的方法

插件npm链接

2 项目中使用该插件的原因

主要是在react项目中，在自定义的组件上使用了mobox，设置了observer之后，该组件调用的setTimeout等方法，并非windows对象原生的方法，而是native function，所以import了该插件中的相关方法，从而实现原生的定时器功能

3 相关源码

var scope = (typeof global !== "undefined" && global) ||
            (typeof self !== "undefined" && self) ||
            window;
var apply = Function.prototype.apply;

// DOM APIs, for completeness

exports.setTimeout = function() {
  return new Timeout(apply.call(setTimeout, scope, arguments), clearTimeout);
};
exports.setInterval = function() {
  return new Timeout(apply.call(setInterval, scope, arguments), clearInterval);
};
exports.clearTimeout =
exports.clearInterval = function(timeout) {
  if (timeout) {
    timeout.close();
  }
};

function Timeout(id, clearFn) {
  this._id = id;
  this._clearFn = clearFn;
}
Timeout.prototype.unref = Timeout.prototype.ref = function() {};
Timeout.prototype.close = function() {
  this._clearFn.call(scope, this._id);
};

// Does not start the time, just sets up the members needed.
exports.enroll = function(item, msecs) {
  clearTimeout(item._idleTimeoutId);
  item._idleTimeout = msecs;
};

exports.unenroll = function(item) {
  clearTimeout(item._idleTimeoutId);
  item._idleTimeout = -1;
};

exports._unrefActive = exports.active = function(item) {
  clearTimeout(item._idleTimeoutId);

  var msecs = item._idleTimeout;
  if (msecs >= 0) {
    item._idleTimeoutId = setTimeout(function onTimeout() {
      if (item._onTimeout)
        item._onTimeout();
    }, msecs);
  }
};

// setimmediate attaches itself to the global object
require("setimmediate");
// On some exotic environments, it's not clear which object `setimmediate` was
// able to install onto.  Search each possibility in the same order as the
// `setimmediate` library.
exports.setImmediate = (typeof self !== "undefined" && self.setImmediate) ||
                       (typeof global !== "undefined" && global.setImmediate) ||
                       (this && this.setImmediate);
exports.clearImmediate = (typeof self !== "undefined" && self.clearImmediate) ||
                         (typeof global !== "undefined" && global.clearImmediate) ||
                         (this && this.clearImmediate);