/**
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* @fileoverview collections of some technic methods.
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* @author NHN.
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* FE Development Lab <dl_javascript.nhn.com>
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*/
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'use strict';
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var tricks = {};
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var aps = Array.prototype.slice;
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/**
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* Creates a debounced function that delays invoking fn until after delay milliseconds has elapsed
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* since the last time the debouced function was invoked.
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* @param {function} fn The function to debounce.
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* @param {number} [delay=0] The number of milliseconds to delay
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* @memberof tui.util
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* @returns {function} debounced function.
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* @example
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* //-- #1. Get Module --//
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* var util = require('tui-code-snippet'); // node, commonjs
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* var util = tui.util; // distribution file
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*
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* //-- #2. Use property --//
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* function someMethodToInvokeDebounced() {}
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*
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* var debounced = util.debounce(someMethodToInvokeDebounced, 300);
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*
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* // invoke repeatedly
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* debounced();
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* debounced();
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* debounced();
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* debounced();
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* debounced();
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* debounced(); // last invoke of debounced()
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*
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* // invoke someMethodToInvokeDebounced() after 300 milliseconds.
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*/
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function debounce(fn, delay) {
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var timer, args;
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/* istanbul ignore next */
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delay = delay || 0;
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function debounced() { // eslint-disable-line require-jsdoc
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args = aps.call(arguments);
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window.clearTimeout(timer);
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timer = window.setTimeout(function() {
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fn.apply(null, args);
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}, delay);
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}
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return debounced;
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}
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/**
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* return timestamp
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* @memberof tui.util
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* @returns {number} The number of milliseconds from Jan. 1970 00:00:00 (GMT)
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*/
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function timestamp() {
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return Number(new Date());
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}
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/**
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* Creates a throttled function that only invokes fn at most once per every interval milliseconds.
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*
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* You can use this throttle short time repeatedly invoking functions. (e.g MouseMove, Resize ...)
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*
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* if you need reuse throttled method. you must remove slugs (e.g. flag variable) related with throttling.
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* @param {function} fn function to throttle
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* @param {number} [interval=0] the number of milliseconds to throttle invocations to.
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* @memberof tui.util
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* @returns {function} throttled function
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* @example
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* //-- #1. Get Module --//
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* var util = require('tui-code-snippet'); // node, commonjs
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* var util = tui.util; // distribution file
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*
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* //-- #2. Use property --//
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* function someMethodToInvokeThrottled() {}
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*
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* var throttled = util.throttle(someMethodToInvokeThrottled, 300);
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*
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* // invoke repeatedly
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* throttled(); // invoke (leading)
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* throttled();
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* throttled(); // invoke (near 300 milliseconds)
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* throttled();
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* throttled();
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* throttled(); // invoke (near 600 milliseconds)
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* // ...
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* // invoke (trailing)
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*
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* // if you need reuse throttled method. then invoke reset()
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* throttled.reset();
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*/
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function throttle(fn, interval) {
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var base;
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var isLeading = true;
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var tick = function(_args) {
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fn.apply(null, _args);
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base = null;
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};
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var debounced, stamp, args;
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/* istanbul ignore next */
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interval = interval || 0;
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debounced = tricks.debounce(tick, interval);
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function throttled() { // eslint-disable-line require-jsdoc
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args = aps.call(arguments);
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if (isLeading) {
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tick(args);
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isLeading = false;
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return;
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}
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stamp = tricks.timestamp();
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base = base || stamp;
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// pass array directly because `debounce()`, `tick()` are already use
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// `apply()` method to invoke developer's `fn` handler.
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//
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// also, this `debounced` line invoked every time for implements
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// `trailing` features.
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debounced(args);
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if ((stamp - base) >= interval) {
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tick(args);
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}
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}
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function reset() { // eslint-disable-line require-jsdoc
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isLeading = true;
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base = null;
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}
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throttled.reset = reset;
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return throttled;
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}
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tricks.timestamp = timestamp;
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tricks.debounce = debounce;
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tricks.throttle = throttle;
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module.exports = tricks;
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