2016-04-18 17:20:30 -04:00
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/**
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2016-09-12 13:09:01 -04:00
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* @fileoverview
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* A utility for accurately measuring time.
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* To use:
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* ---
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* var timer = new Timer();
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* timer.start();
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* ... pass some time ...
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* var timeDifference = timer.timeElapsed();
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* ---
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* Or, you can use the `time` and `relativeTime`
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* to do some measurement yourself.
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2016-04-18 17:20:30 -04:00
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*/
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2017-04-17 19:42:48 -04:00
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class Timer {
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2018-12-04 10:35:42 -05:00
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constructor (nowObj = Timer.nowObj) {
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2017-04-17 19:42:48 -04:00
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/**
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* Used to store the start time of a timer action.
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* Updated when calling `timer.start`.
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*/
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this.startTime = 0;
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2018-12-04 10:35:42 -05:00
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/**
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* Used to pass custom logic for determining the value for "now",
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* which is sometimes useful for compatibility with Scratch 2
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*/
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this.nowObj = nowObj;
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2017-04-17 19:42:48 -04:00
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}
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2016-09-12 13:09:01 -04:00
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2017-04-17 19:42:48 -04:00
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/**
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* Disable use of self.performance for now as it results in lower performance
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* However, instancing it like below (caching the self.performance to a local variable) negates most of the issues.
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* @type {boolean}
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*/
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static get USE_PERFORMANCE () {
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return false;
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}
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2017-02-08 03:11:10 -05:00
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2017-04-17 19:42:48 -04:00
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/**
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* Legacy object to allow for us to call now to get the old style date time (for backwards compatibility)
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* @deprecated This is only called via the nowObj.now() if no other means is possible...
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*/
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static get legacyDateCode () {
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return {
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now: function () {
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return new Date().getTime();
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}
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};
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2017-02-08 03:11:10 -05:00
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}
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2017-04-17 19:42:48 -04:00
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/**
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* Use this object to route all time functions through single access points.
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*/
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static get nowObj () {
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if (Timer.USE_PERFORMANCE && typeof self !== 'undefined' && self.performance && 'now' in self.performance) {
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return self.performance;
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} else if (Date.now) {
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return Date;
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}
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return Timer.legacyDateCode;
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}
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2017-02-08 03:11:10 -05:00
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2017-04-17 19:42:48 -04:00
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/**
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* Return the currently known absolute time, in ms precision.
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* @returns {number} ms elapsed since 1 January 1970 00:00:00 UTC.
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*/
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time () {
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2018-12-04 10:35:42 -05:00
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return this.nowObj.now();
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2017-04-17 19:42:48 -04:00
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}
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2016-04-18 17:20:30 -04:00
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2017-04-17 19:42:48 -04:00
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/**
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* Returns a time accurate relative to other times produced by this function.
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* If possible, will use sub-millisecond precision.
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* If not, will use millisecond precision.
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* Not guaranteed to produce the same absolute values per-system.
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* @returns {number} ms-scale accurate time relative to other relative times.
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*/
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relativeTime () {
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2018-12-04 10:35:42 -05:00
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return this.nowObj.now();
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2017-04-17 19:42:48 -04:00
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}
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2016-09-12 13:09:01 -04:00
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2017-04-17 19:42:48 -04:00
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/**
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* Start a timer for measuring elapsed time,
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* at the most accurate precision possible.
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*/
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start () {
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2018-12-04 10:35:42 -05:00
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this.startTime = this.nowObj.now();
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2017-04-17 19:42:48 -04:00
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}
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2016-04-18 17:20:30 -04:00
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2017-04-17 19:42:48 -04:00
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timeElapsed () {
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2018-12-04 10:35:42 -05:00
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return this.nowObj.now() - this.startTime;
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2017-04-17 19:42:48 -04:00
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}
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}
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2016-04-18 17:20:30 -04:00
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module.exports = Timer;
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