JavaScript for Web Analysts

JavaScript for Web Analytics Beginners Guide by Lukáš Čech

Lukáš Čech (in numbers) Male human (35) Internet (20) Etnetera (11) Analytics (8) Father (4) MeasureCamp (3) Double father (2) *) as of 16.9.2017

Inspired by Principy JavaScriptu by Riki Fridrich

JavaScript is a high-level, dynamic, weakly typed, object- based, multi-paradigm, and interpreted programming language.

High-level Dynamic Interpreted

var x = [0]; x == x // true x == !x // true ['',''] == ',' // true ['',''] === ',' // false '5' - 3 // 2 '5' + 3 // 53

The basics of the basics – Primitive types Undefined Null Boolean Number String

The basics – Reference types Object*) (Associative Array) → Array → Function (IIFE1) Regex *) JSON2

Primitive var key = 1; function add (input) { input++; } add(key); console.log(key); // 1 var obj = {key: 1}; function add (input) { input.key++; } add(obj); console.log(obj.key); // 2 Reference

var obj = {key: 1}; function add (input) { input.key++; } add(JSON.parse(JSON.stringify(obj))); console.log(obj.key); // 1

length slice(start, end) substring(start, end) substr(start, length) indexOf(), lastIndexOf() split(separator), concat() search(), replace() Array Methods and PropertiesString Methods and Properties length push(item), pop() shift(), unshift() slice(), splice() indexOf() join(), concat() sort(), reverse()

Operations & Comparisons +, -, *, /, %, ++, -- =, +=, -=, *=, /=, %= ==, ===, !=, !==, <, >, >=, <= &&, ||, !, typeof, instanceof ? &, |, ~, ^, <<, >>, >>> Still the basics

Control Structures Functions if-else, switch for, for/in while, do/while try..catch, throw

The almost-nerdy stuff Hoisting Scope Scope Chain call(), apply(), bind() this Closure

function logString () { var string = 'a'; console.log(string); }; logString(); // a console.log(string); // Uncaught ReferenceError // 'string' doesn't exist in global scope var string; string = 'a'; function logString () { console.log(string); }; logString(); // a Scope ChainGlobal Vs. Function Scope

for (var i=0; i<3; i++) { setTimeout(function() { console.log(i); }, 0); } // 3 // 3 // 3 function async (i) { setTimeout(function() { console.log(i); }, 0); }; for (var i=0; i<3; i++) { async(i); } // 0 // 1 // 2 Calling function creates own scopeClosure is created

The nerdy stuff Event Loop Events Callbacks

console.log('start'); setTimeout(function() { console.log('hello from callback'); }, 0); console.log('end'); // "start" // "end" // "hello from callback"

The sooo-nerdy stuff Async AJAX JSONP / CORS

Honey, bring me a beer!!! Async 🙌

Neighboring Galaxies Tag Management, HTTP, DNS, SSL, Cookies, HTML/DOM, Browsers, Console, Local Storage, API, REST, jQuery Web servers, Databases, Node.js, Mobile, Linters, Package Managers, Bundlers, Task Runners, Selenium, PhantomJS, CasperJS, Charles Proxy, VCS, Babel, React,...

Don't try this at home "use strict"; Prototypal inheritance Promises ECMAScript 6+ Immutable Stateless JS

JavaScript for Web Analysts

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