1. Variables and Data Types

• Number: Floating point numbers, for decimals and integers
• String: Sequence of characters, used for text
• Boolean: Logical data type that can only be true or false
• Undefined: Data type of a variable that does not have a value yet
• Null: Also means 'non- existent'

2. Variables Mutation and Type Coercion

var firstName = 'john';
var age = 28;

console.log(firstName+age);

var job, isMarried;

job = 'teacher';

isMarried = false;

console.log(job+isMarried);

var lastName = prompt('what is his last name?');

console.log(lastName);

3. Basic Operators

var year, yearJohn ,yearMark;
year = 2018;
ageJohn = 28;
ageMark = 33;

//Math Operators
year = 2018;
yearJohn = year - ageJohn;
yearMark = year - ageMark;
console.log(yearJohn, yearMark);

//Logical Operators
var johnOlder = ageJohn > ageMark;
console.log(johnOlder);

//Typeof Operators
console.log(typeof johnOlder);
console.log(typeof ageJohn);
console.log(typeof x);

4. Operator Precedence

5. Falsy and Truthy values

Falsy values:

• undefined
• null
• 0
• ''
• ""
• NaN

Truthy values:

• not falsy values

• ---

  6. Equality Operators

• ==

•        "==" does type coercoion (it converts the string to a number)

• === (more strict)

•        "==="does NOT coercoion