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* 提供倒计时器统一封装
* @method time/countDown
* @param {Object} spec 选项
* @param {Date} [spec.base] 矫正时间，如果需要用服务端时间矫正倒计时，使用此参数
* @param {Date} [spec.target=Date.now() + 3000] 目标时间
* @param {Number} [spec.interval=1000] 倒计时触发间隔
* @param {Function} [spec.onChange] 倒计时触发变更的事件回调
* @param {Function} [spec.onStop] 倒计时结束的回调
* @returns {Object} 倒计时对象实例
* @example
* var $countDown = require('@spore-ui/kit/packages/time/countDown');
* var target = Date.now() + 5000;
* var cd1 = $countDown({
* target : target,
* onChange : function(delta){
* console.info('cd1 change', delta);
* },
* onStop : function(delta){
* console.info('cd1 stop', delta);
* }
* });
* setTimeout(function(){
* //trigger stop
* cd1.stop();
* }, 2000);
* var cd2 = countDown({
* target : target,
* interval : 2000,
* onChange : function(delta){
* console.info('cd2 change', delta);
* },
* onStop : function(delta){
* console.info('cd2 stop', delta);
* }
* });
*/
var $erase = require('../arr/erase');
var $assign = require('../obj/assign');
var allMonitors = {};
var localBaseTime = Date.now();
function countDown(spec) {
var that = {};
// 为什么不使用 timeLeft 参数替换 base 和 target:
// 如果用 timeLeft 作为参数，计时器初始化之前如果有进程阻塞，有可能会导致与目标时间产生误差
// 页面多个定时器一起初始化时，会出现计时器更新不同步的现象，同时引发页面多处没有一起回流
// 保留目前这个方案，用于需要精确倒计时的情况
var conf = $assign({
base: null,
target: Date.now() + 3000,
interval: 1000,
onChange: null,
onStop: null,
}, spec);
var timeDiff = 0;
var target = +new Date(conf.target);
var interval = parseInt(conf.interval, 10) || 0;
var onChange = conf.onChange;
var onStop = conf.onStop;
// 使倒计时触发时间精确化
// 使用固定的触发频率，减少需要创建的定时器
var timeInterval = interval;
Eif (timeInterval < 500) {
timeInterval = 10;
} else if (timeInterval < 5000) {
timeInterval = 100;
} else {
timeInterval = 1000;
}
var delta;
var curUnit;
var update = function (now) {
delta = target - now;
var unit = Math.ceil(delta / interval);
if (unit !== curUnit) {
curUnit = unit;
Eif (typeof onChange === 'function') {
onChange(delta);
}
}
};
/**
* 重设目标时间
* @method countDown#setTarget
* @memberof time/countDown
* @example
* var cd = countDown();
* var localTime = '2019/01/01';
* cd.setTarget(serverTime);
*/
that.setTarget = function (time) {
target = +new Date(time);
};
/**
* 纠正时间差
* @method countDown#correct
* @memberof time/countDown
* @example
* var cd = countDown();
* var serverTime = '2019/01/01';
* var localTime = '2020/01/01';
* cd.correct(serverTime);
* cd.correct(serverTime, localTime);
*/
that.correct = function (serverTime, localTime) {
var now = localTime ? new Date(localTime) : +new Date();
var serverDate = serverTime ? new Date(serverTime) : 0;
Eif (serverDate) {
timeDiff = serverDate - now;
}
};
if (conf.base) {
that.correct(conf.base);
}
var check = function (localDelta) {
var now = localBaseTime + timeDiff + localDelta;
update(now);
if (delta <= 0) {
that.stop(now);
}
};
/**
* 停止倒计时
* @method countDown#stop
* @memberof time/countDown
* @example
* var cd = countDown();
* cd.stop();
*/
that.stop = function () {
var mobj = allMonitors[timeInterval];
Eif (mobj && mobj.queue) {
$erase(mobj.queue, check);
}
// onStop事件触发必须在从队列移除回调之后
// 否则循环接替的定时器会引发死循环
if (typeof onStop === 'function') {
onStop(delta);
}
};
/**
* 销毁倒计时
* @method countDown#destroy
* @memberof time/countDown
* @example
* var cd = countDown();
* cd.destroy();
*/
that.destroy = function () {
onChange = null;
onStop = null;
that.stop();
};
var monitor = allMonitors[timeInterval];
if (!monitor) {
monitor = {};
monitor.queue = [];
monitor.inspect = function () {
var now = Date.now();
var mobj = allMonitors[timeInterval];
var localDelta = now - localBaseTime;
if (mobj.queue.length) {
// 循环当中会删除数组元素，因此需要先复制一下数组
mobj.queue.slice(0).forEach(function (fn) {
fn(localDelta);
});
} else {
clearInterval(mobj.timer);
allMonitors[timeInterval] = null;
delete mobj.timer;
}
};
allMonitors[timeInterval] = monitor;
}
monitor.queue.push(check);
if (!monitor.timer) {
monitor.timer = setInterval(monitor.inspect, timeInterval);
}
monitor.inspect();
return that;
}
countDown.allMonitors = allMonitors;
module.exports = countDown;
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