Java Script

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Basics

Console I/O

console.log("Hello World!");
prompt("What is your name?");

Comments

// This is a single line comment.
/* This is a really long comment
that extends multiple lines */

Variables

var a = 0;
Types
var aNumber = 21;

var aString = "Ben";

var aBool = true;
Type Conversions:

Operators

Operation Syntax
addition 1 + 2
subtraction 1 - 2
multiplication 1 * 2
division 1 / 2
modulus 1 % 2
increment a++
decrement a--

Comparison

Operation Syntax
equal a == b
not equal a != b
greater than a > b
less than a < b
greater than or equal to a >= b
less than or equal to a <= b

Logical

Operation Syntax
and a && b
or a || b
not !a

Conditionals

if (name == "Joe") {
//...
} else if (name == "Bob") {
//...
} else {
//...
}

(name == "Joe") ? /* if part */ : /* else part */

switch (name) {
case "Joe":
    break;
case "Bob":
    break;
default:
    break;
}

Loops:

for (var i = 0; i < 100; i++) {
// ...
}

for (var val of ["a", "b", "c"]) {
// ...
}

while (condition == true) {
// ...
}

do {
// ...
} while (condition == true);

Functions

function (a) {
return a + 100;
}

(a, b) => a + b;

Classes

class aClass {
    aPublicField = "hi everyone!";
    #aPrivateField = "shh! secret";
    constructor(param) {
    this.aPublicField = param;
    //...
    }
    
    randomMethod() {
    //...
    }
    
    //getter
    get someProp() {
    return null;
    }
    
    //static
    static printHi() {
    console.log("Hi");
    }
}

class aChild extends aClass {
    constructor(otherParam) {
    super(otherParam);
    }
    
    // overridden method
    randomMethod() {
    // other stuff...
    }
}

var myObj = new aClass("foo");

Advanced

Arrays/Lists

var myArr = [a, b, c];

var myDict = {key1: 1, key2: 2, key3: 3};
Function Syntax
search indexOf(val)
push, pop push(val) pop()
insert splice(start[, deleteCount, items...])
concatenate concat(arr)
subarray slice(start[, length])
sort sort([compareFunc(first, second)])
loop use for...of loop
map map(callback(currentValue[, index, array]))

Strings

Function Syntax
search indexOf(subStr)
insert not available
replace replace(pattern, replacement)
concatenate "a string" + " another string"
substring slice(start[, length])

Math

Math.PI

Math.E
Function Syntax
square root sqrt()
exponentiation pow(a, b)
random number random()
absolute value abs(a)
round round(a)
ceiling ceil(a)
floor floor(a)
max max(a, b)
min min(a, b)
sine sin(a)
cosine cos(a)
tangent tan(a)
arcsine asin(a)
arccosine acos(a)
arctangent atan(a)

Dates

...

Files

...

Bitwise Operations

Operation Syntax
AND a & b
OR a | b
XOR a ^ b
NOT a ~ b
Left Shift a << b
Right Shift a >> b
Zero fill right shift a >>> b

Errors

try {
// ...
} catch (e) {
// ...
} finally {
// ...
}

throw new Error(message);

Extra

...