JavaScripting

javascripting.md

Nodeschool.io JavaScripting

Introduction

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Variables

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Strings

• Looks like convention in JavaScript is to use single quotes.

String Length

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Revising Strings

• JavaScript has a .replace() method that takes two arguments. The first argument is an existing substring and the second is the string that will replace it.

Numbers

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Rounding Numbers

• To round numbers in JavaScript we use the Math object along with the .round() method and pass it in the float we want rounded.

Number to String

• We use the .toString() method to convert a number to a string.

If Statement

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For Loop

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Arrays

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Array Filtering

• We use the .filter() method to filter an array based on a condition.

var filtered = numbers.filter(function(num) {
  return num % 2 === 0;
});

Accessing Array Values

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Looping Through Arrays

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Objects

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Object Properties

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Functions

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Function Arguments

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Scope

• Scope is the set of variables, objects, and functions you have access to.
• JavaScript has two scopes: global and local.
• A variable that is declared outside a function definition is a global variable, and its value is accessible and modifiable throughout your program.
• A variable that is declared inside a function definition is local. It is created and destroyed everytime the function is executed, and it cannot be accessed by any code outside the function.
• Functions defined inside other functions, known as nested functions, have access to their parent function's scope.
• IIFE, Immediately Invoked Function Expression, is a common pattern for creating local scopes.

(function() {
})();