Sample-Technical-Documentation-Page/index.html at master · ArdeshirV/Sample-Technical-Documentation-Page · GitHub

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<!DOCTYPE html>
<html lang="en-US">

<head>
  <meta charset="UTF-8">
  <title>JavaScript Syntax Overview - Sample Technical Documentation</title>
  <!--<link rel="stylesheet" href="https://raw.githubusercontent.com/ArdeshirV/ardeshirv.github.io/master/css/av-darklee.css">-->
  <link rel="stylesheet" href="./css/av-darklee.css">
  <link rel="stylesheet" href="./css/style.css">
  <link rel="icon" href="img/tech-supp.png">
  <script src="https://cdn.freecodecamp.org/testable-projects-fcc/v1/bundle.js">
  </script>
</head>

<body>
  <div class="div-main-flex" id="main-div">
    <nav id="navbar">
      <header>
        <h1>JavaScript Syntax Overview</h1>
      </header>
      <div class="links">
        <a class="nav-link" href="#Simple_Examples">Simple examples</a>
        <a class="nav-link" href="#Data_Types_in_JavaScript">Data Types in JavaScript</a>
        <a class="nav-link" href="#Console_Object">Console Object</a>
        <a class="nav-link" href="#Recursive_Function">Recursive Function</a>
        <a class="nav-link" href="#Anonymous_Function">Anonymous Function</a>
        <a class="nav-link" href="#Arrow_Functions">Arrow Functions</a>
        <a class="nav-link" href="#Objects_in_JavaScript">Objects in JavaScript</a>
        <a class="nav-link" href="#Variadic_Function">Variadic Function</a>
        <a class="nav-link" href="#Immediately_Invoked_Function_Expressions">Immediately Invoked Function
          Expressions</a>
        <a class="nav-link" href="#Exporting_and_Importing_Modules">Exporting and Importing Modules</a>
        <a class="nav-link" href="#More_Advanced_Example">More Advanced Example</a>
      </div>
      <br />
      <h5 class="h5-description">Description</h5>
      <p class="p-description">
        JavaScript (/ˈdʒɑːvəˌskrɪpt/), often abbreviated as JS, is a programming language that conforms to the
        ECMAScript specification. JavaScript is high-level, often just-in-time compiled, and multi-paradigm. It has
        curly-bracket syntax, dynamic typing, prototype-based object-orientation, and first-class functions.
      </p>
    </nav>

    <main id="main-doc">
      <section id="Simple_Examples" class="main-section">
        <header name="header">
          <h2>Simple examples</h2>
        </header>
        <p>
          Variables in JavaScript can be defined using either the var, let or const keywords.
        </p>
        <code>
// Declares a function-scoped variable named `x`, and implicitly assigns the
// special value `undefined` to it. Variables without value are automatically
// set to undefined.
var x;

// Variables can be manually set to `undefined` like so
var x2 = undefined;

// Declares a block-scoped variable named `y`, and implicitly sets it to
// `undefined`. The `let` keyword was introduced in ECMAScript 2015.
let y;

// Declares a block-scoped, un-reassign-able variable named `z`, and sets it to
// a string literal. The `const` keyword was also introduced in ECMAScript 2015,
// and must be explicitly assigned to.

// The keyword `const` means constant, hence the variable cannot be reassigned
// as the value is `constant`.
const z = "this value cannot be reassigned!";

// Declares a variable named `myNumber`, and assigns a number literal (the value
// `2`) to it.
let myNumber = 2;

// Reassigns `myNumber`, setting it to a string literal (the value `"foo"`).
// JavaScript is a dynamically-typed language, so this is legal.
myNumber = "foo";
        </code>
        <p>
          Note the comments in the example above, all of which were preceded with two forward slashes.
          There is no built-in Input/output functionality in JavaScript; the run-time environment provides that. The
          ECMAScript specification in edition 5.1
          indeed, there are no provisions in this specification for input of external data or output of computed
          results.
        </p>
        <hr>
      </section>

      <section id="Data_Types_in_JavaScript" class="main-section">
        <header name="header">
          <h2>Data Types in JavaScript</h2>
        </header>
        <p>
          These are data types in JavaScript:
        </p>
        <ul>
          <li>undefined</li>
          <li>null</li>
          <li>boolean</li>
          <li>string</li>
          <li>bigint</li>
          <li>number</li>
          <li>object</li>
        </ul>
        <hr>
      </section>

      <section id="Console_Object" class="main-section">
        <header name="header">
          <h2>Console Object</h2>
        </header>
        <p>
          However, most runtime environments have a console object that can be used to print output. Here is a
          minimalist Hello World program in JavaScript:
        </p>
        <code>
console.log("Hello World!");
        </code>
        <hr>
      </section>

      <section id="Recursive_Function" class="main-section">
        <header name="header">
          <h2>Recursive Function</h2>
        </header>
        <p>A simple recursive function:</p>
        <code>
function factorial(n) {
  if (n === 0)
    return 1; // 0! = 1
  return n * factorial(n - 1);
}

factorial(3); // returns 6
        </code>
        <hr>
      </section>

      <section id="Anonymous_Function" class="main-section">
        <header name="header">
          <h2>Anonymous Function</h2>
        </header>
        <p>
          An <a href="https://en.wikipedia.org/wiki/Anonymous_function" target="_blank">anonymous function</a> (or
          lambda):
        </p>
        <code>
function counter() {
  let count = 0;

  return function() {
    return ++count;
  };
}

let closure = counter();
closure(); // returns 1
closure(); // returns 2
closure(); // returns 3
        </code>
        <p>This example shows that, in JavaScript, <a
            href="https://en.wikipedia.org/wiki/Closure_(computer_programming)" target="_blank">function closures</a>
          capture their non-local variables by reference.</p>
        <hr>
      </section>

      <section id="Arrow_Functions" class="main-section">
        <header name="header">
          <h2>Arrow Functions</h2>
        </header>
        <p>
          Arrow functions were first introduced in 6th Edition - <a
            href="https://en.wikipedia.org/wiki/ECMAScript#6th_Edition_-_ECMAScript_2015" target="_blank">ECMAScript
            2015</a>. They shorten the syntax for writing functions in JavaScript. Arrow functions are anonymous in
          nature; a variable is needed to refer to them in order to invoke them after their creation.
        </p>
        <p>Example of arrow function:</p>
        <code>
// Arrow functions let us omit the `function` keyword. Here `long_example`
// points to an anonymous function value.
const long_example = (input1, input2) => {
  console.log("Hello, World!");
  const output = input1 + input2;

  return output;
};

// Arrow functions also let us automatically return the expression to the right
// of the arrow (here `input + 5`), omitting braces and the `return` keyword.
const short_example = (input,input2) => input + input2;

long_example(2, 3); // Prints "Hello, World!" and returns 5.
short_example(2, 5); // Returns 7.

// If an arrow function only has one parameter, the parenthesis can be removed.
const no_parenthesis = input => input + 2;

no_parenthesis(3); // Returns 5.
        </code>
        <hr>
      </section>

      <section id="Objects_in_JavaScript" class="main-section">
        <header name="header">
          <h2>Objects in JavaScript</h2>
        </header>
        <p>
          In JavaScript, objects are created in the same way as functions; this is known as a function object.
        </p>
        <p>Object example:</p>
        <code>
function Ball(r) {
  this.radius = r; // the radius variable is local to the ball object
  this.area = Math.PI * r ** 2;
  this.show = function(){ // objects can contain functions
    drawCircle(r); // references a circle drawing function
  }
}

let myBall = new Ball(5); // creates a new instance of the ball object with radius 5
myBall.radius++; // properties exposed with "this" can be modified from the outside
myBall.show(); // this instance of the ball object has the show function performed on it
        </code>
        <hr>
      </section>

      <section id="Variadic_Function" class="main-section">
        <header name="header">
          <h2>Variadic Function</h2>
        </header>
        <p>
          <a href="https://en.wikipedia.org/wiki/Variadic_function" target="_blank">Variadic function</a> demonstration
          (arguments is a special variable):[63]
        </p>
        <code>
function sum() {
  let x = 0;

  for (let i = 0; i &#60; arguments.length; ++i)
    x += arguments[i];

  return x;
}

sum(1, 2); // returns 3
sum(1, 2, 3); // returns 6
        </code>
        <hr>
      </section>

      <section id="Immediately_Invoked_Function_Expressions" class="main-section">
        <header name="header">
          <h2>Immediately Invoked Function Expressions</h2>
        </header>
        <p>
          <a href="https://en.wikipedia.org/wiki/Immediately-invoked_function_expression"
            target="_blank">Immediately-invoked function expressions</a> are often used to create modules; before
          ECMAScript 2015 there was no built-in module construct in the language. Modules allow gathering properties and
          methods in a namespace and making some of them private:
        </p>
        <code>
let counter = (function() {
  let i = 0; // private property

  return { // public methods
    get: function() {
      alert(i);
    },
    set: function(value) {
      i = value;
    },
    increment: function() {
      alert(++i);
    }
  };
})(); // module

counter.get(); // shows 0
counter.set(6);
counter.increment(); // shows 7
counter.increment(); // shows 8
        </code>
        <hr>
      </section>

      <section id="Exporting_and_Importing_Modules" class="main-section">
        <header name="header">
          <h2>Exporting and Importing Modules</h2>
        </header>
        <p>
          Exporting and Importing modules in JavaScript.
        </p>
        <code>
/* mymodule.js */
// This function remains private, as it is not exported
let sum = (a, b) => {
  return a + b;
}

// Export variables
export let name = 'Alice';
export let age = 23;

// Export named functions
export function add(num1, num2){
  return num1 + num2;
}

// Export class
export class Multiplication {
    constructor(num1, num2) {
      this.num1 = num1;
      this.num2 = num2;
  }

  add() {
    return sum(this.num1, this.num2);
  }
}
        </code>
        <p>Import example:</p>
        <code>
// Import one property
import { add } from './mymodule.js';

console.log(add(1, 2)); // 3

// Import multiple properties
import { name, age } from './mymodule.js';
console.log(name, age);
//> "Alice", 23

// Import all properties from a module
import * from './module.js'
console.log(name, age);
//> "Alice", 23
console.log(add(1,2));
//> 3
        </code>
        <hr>
      </section>

      <section id="More_Advanced_Example" class="main-section">
        <header name="header">
          <h2>More Advanced Example</h2>
        </header>
        <p>
          This sample code displays various JavaScript features.
        </p>
        <code>
/* Finds the lowest common multiple (LCM) of two numbers */
function LCMCalculator(x, y) { // constructor function
  let checkInt = function(x) { // inner function
    if (x % 1 !== 0)
    throw new TypeError(x + "is not an integer"); // var a = mouseX

    return x;
  };

  this.a = checkInt(x)
  // semicolons ^^^^ are optional, a newline is enough
  this.b = checkInt(y);
}

// The prototype of object instances created by a constructor is
// that constructor's "prototype" property.
LCMCalculator.prototype = { // object literal
  constructor: LCMCalculator, // when reassigning a prototype, set the constructor property appropriately
    gcd: function() { // method that calculates the greatest common divisor
    // Euclidean algorithm:
    let a = Math.abs(this.a), b = Math.abs(this.b), t;

    if (a &#60; b) {
      // swap variables
      // t = b; b = a; a = t;
      [a, b] = [b, a]; // swap using destructuring assignment (ES6)
    }

    while (b !== 0) {
      t = b;
      b = a % b;
      a = t;
    }

    // Only need to calculate GCD once, so "redefine" this method.
    // (Actually not redefinition—it's defined on the instance itself,
    // so that this.gcd refers to this "redefinition" instead of LCMCalculator.prototype.gcd.
    // Note that this leads to a wrong result if the LCMCalculator object members "a" and/or "b" are altered
    afterwards.)
    // Also, 'gcd' === "gcd", this['gcd'] === this.gcd
    this['gcd'] = function() {
    return a;
    };

    return a;
  },

  // Object property names can be specified by strings delimited by double (") or single (') quotes.
  lcm: function() {
    // Variable names do not collide with object properties, e.g., |lcm| is not |this.lcm|.
    // not using |this.a*this.b| to avoid FP precision issues
    let lcm = this.a / this.gcd() * this.b;

    // Only need to calculate lcm once, so "redefine" this method.
    this.lcm = function() {
      return lcm;
    };

    return lcm;
  },

  toString: function() {
    return "LCMCalculator: a = " + this.a + ", b = " + this.b;
  }
};

// Define generic output function; this implementation only works for Web browsers
function output(x) {
  document.body.appendChild(document.createTextNode(x));
  document.body.appendChild(document.createElement('br'));
}

// Note: Array's map() and forEach() are defined in JavaScript 1.6.
// They are used here to demonstrate JavaScript's inherent functional nature.
[
  [25, 55],
  [21, 56],
  [22, 58],
  [28, 56]
].map(function(pair) { // array literal + mapping function
  return new LCMCalculator(pair[0], pair[1]);
}).sort((a, b) => a.lcm() - b.lcm()) // sort with this comparative function; => is a shorthand form of a
  function, called "arrow function"
  .forEach(printResult);

function printResult(obj) {
  output(obj + ", gcd = " + obj.gcd() + ", lcm = " + obj.lcm());
}
        </code>
        <p>The following output should be displayed in the browser window.</p>
        <code>
LCMCalculator: a = 28, b = 56, gcd = 28, lcm = 56
LCMCalculator: a = 21, b = 56, gcd = 7, lcm = 168
LCMCalculator: a = 25, b = 55, gcd = 5, lcm = 275
LCMCalculator: a = 22, b = 58, gcd = 2, lcm = 638
        </code>
      </section>

      <footer>
        <p class="footer-p" target="_blank">All the documentation in this page is taken from <a
            href="https://en.wikipedia.org/wiki/JavaScript">wikipedia</a></p>
        <p class="footer-p">
          Copyright&copy; 2020 <a href="mailto:ArdeshirV@protonmail.com" alt="email">ArdeshirV@protonmail.com</a>,
          Licensed under GPL<sup>v3+</sup>
        </p>
      </footer>
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