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Is a cross-platform, object-oriented scripting language used to make webpages interactive.

Javascript	Java
not strict	very strict
browser-only	JVM
OOP Scriping - prototype	Classic OOP

Arrays - is a global object that is used in the construction of arrays; which are high-level, list-like objects.

• Inherits from Object
• Performance is good with small data set
• Can be modified, length not fixed

var languages = ['PHP', 'JAVA', 'Python'];

Variables

• var - global scope, local scope if initialized in function
• let - block scope
• const - also block scope, but can't be modified
• case sensitive - "var x" & "var X" are two different variables!
• *Best practice - Use "const", if value change then use "let".

Hositing - behavior where variable and function (not expression) declarations gets pushed to the top.

Due to hoisting, "x" gets hoisted to outer scope, therefore "x" value can be retrived.

if (true) {
  var x = 1;
} 
console.log(x) // 1

Due to function (local scope), "x" does not update outer scope, therefore "x" value is not defined.

function foo() {
  var x = 1;
} 
foo();
console.log(x) // not defined

Comments

• Single line:

  // I am a single line comment

• Multi line:

  /* I am a 
      multi line comment */