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Javascript Cheat Sheet (DRAFT) by

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Values

Operators
Strings
Weird Stuff
+, -, *, /, %
"­str­ing­"
infinity
+=, -=, *=, /=
'string'
-infinity
++, --
`string`
NaN
<, <=, >, >=
.length
null, undefined
&&, ||, !
\n
typeof()
+ (concat)
state ? 1 : 2
\t (tab)
==, != (convert)
\"
===, !==
\\
-Backt­ick­-quoted (template literals) ables:
` fourteen is also ${10+4}`
// fourteen is also 14

-Empty strings convert to false when parse to boolean:
"­" = false

-let ,const & var scope with funtions
-var doesnt scope with loops
-let & const scope with loops
  

Program Structure

Condit­ional
Useful Things
if(){}else if(){}­else{}
break
while(){}
continue
do{} while()
//, /* */
for(let i=0;i<­x;i­++){}
switch (x) {
 case 1:
 ­ ­ ­break;
 case "­clo­udy­":
 ­ ­ ­con­sol­e.l­og(­"­Bring umbrel­la."­);
 ­ ­ ­break;
 ­def­ault:
 ­ ­ ­break;
}

Function

// Define a function
const makeNoise = function() {
  console.log("Pling!");
};

// Declaration notation
function makeNoise {
  console.log("Pling!");
};

// Arrow function
const makeNoise = () => {
  console.log("Pling!");
}
-Default value of parameters is undefined.

-Default value of parameters can be change:
function power(­base, exponent = 2) {
 ­ ...
}
  

Variables Control

Convertion
Binding
Number()
let, var, const
String()
prompt()
Boolean()
-A single bind allows multiple values:
let x = 0, y = 'dog';

-Bind names can't begin with numbers:
let 4number = 4; WRONG!

- Bind names may contain:
letters, numbers, ($), (_)

Create Variables

let string = "­x"
let number = 2
let boolean = true
let array = [0, 1]
let object = {
 ­ ­happy : true,
 ­ age : 20
}

Number Object

Number Methods
Number.is­NaN()