Sagar Bajpai SagarBajpai

How to Eyeball Your ‘This’ Context in Javascript

by zach.dev

The early programmer struggles with the Javascript keyword this. But understanding your this context is easier than it seems.

This is all about where a function is invoked. Often, early programmers worry about where the function was declared. Perhaps the function was declared in a specific file or a particular object. Surely this changes it's this!

Nope.

	// http://stackoverflow.com/questions/15829172/stop-chrome-back-forward-two-finger-swipe
	$(document).on('mousewheel', function(e) {
	var $target = $(e.target).closest('.scrollable-h');
	if ($target.scrollLeft () <= 4) {
	$target.scrollLeft(5);
	return false;
	}
	});

	/*
	Demo: https://jsfiddle.net/elky/f6khaf2t/

	<div class="element">
	<div class="truncate">
	Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt
	ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco
	laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in
	voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat
	non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

	const GSTINFORMAT_REGEX = "[0-9]{2}[a-zA-Z]{5}[0-9]{4}[a-zA-Z]{1}[1-9A-Za-z]{1}[Z]{1}[0-9a-zA-Z]{1}";
	const GSTN_CODEPOINT_CHARS = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";

	function validGSTIN(gstin) {
	let isValidFormat = false;
	if (checkPattern(gstin, GSTINFORMAT_REGEX)) {
	isValidFormat = verifyCheckDigit(gstin);
	}
	return isValidFormat;
	}

	//Debounce Function
	function debounce(func, delay){
	clearTimeout(timerId);
	timerId = setTimeout(func, delay);
	}

	function throttling(event, func, delay){
	event.persist(); // if you are using react
	const evt = event;
	if(timerIdT)
	return;

	timerIdT = setTimeout(()=>{
	func(evt);
	timerIdT = undefined;
	}, delay);