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
| Precedence | Operator type | Associativity | Individual operators |
|---|---|---|---|
| 20 | Grouping | n/a | ( … ) |
| 19 | Member Access | left-to-right | … . … |
| Computed Member Access | left-to-right | … [ … ] |
|
new (with argument list) |
n/a | new … ( … ) |
|
| Function Call | left-to-right | … ( … ) |
|
| Optional chaining | left-to-right | ?. |
|
| 18 | new (without argument list) |
right-to-left | new … |
| 17 | Postfix Increment | n/a | … ++ |
| Postfix Decrement | … -- |
||
| 16 | Logical NOT | right-to-left | ! … |
| Bitwise NOT | ~ … |
||
| Unary Plus | + … |
||
| Unary Negation | - … |
||
| Prefix Increment | ++ … |
||
| Prefix Decrement | -- … |
||
typeof |
typeof … |
||
void |
void … |
||
delete |
delete … |
||
await |
await … |
||
| 15 | Exponentiation | right-to-left | … ** … |
| 14 | Multiplication | left-to-right | … * … |
| Division | … / … |
||
| Remainder | … % … |
||
| 13 | Addition | left-to-right | … + … |
| Subtraction | … - … |
||
| 12 | Bitwise Left Shift | left-to-right | … << … |
| Bitwise Right Shift | … >> … |
||
| Bitwise Unsigned Right Shift | … >>> … |
||
| 11 | Less Than | left-to-right | … < … |
| Less Than Or Equal | … <= … |
||
| Greater Than | … > … |
||
| Greater Than Or Equal | … >= … |
||
in |
… in … |
||
instanceof |
… instanceof … |
||
| 10 | Equality | left-to-right | … == … |
| Inequality | … != … |
||
| Strict Equality | … === … |
||
| Strict Inequality | … !== … |
||
| 9 | Bitwise AND | left-to-right | … & … |
| 8 | Bitwise XOR | left-to-right | … ^ … |
| 7 | Bitwise OR | left-to-right | … | … |
| 6 | Logical AND | left-to-right | … && … |
| 5 | Logical OR | left-to-right | … || … |
| 4 | Conditional | right-to-left | … ? … : … |
| 3 | Assignment | right-to-left | … = … |
… += … |
|||
… -= … |
|||
… **= … |
|||
… *= … |
|||
… /= … |
|||
… %= … |
|||
… <<= … |
|||
… >>= … |
|||
… >>>= … |
|||
… &= … |
|||
… ^= … |
|||
… |= … |
|||
| 2 | yield |
right-to-left | yield … |
yield* |
yield* … |
||
| 1 | Comma / Sequence | left-to-right | … , … |