Javascript cheat sheet

java_cheat

//Math
Math.round(.6)
Math.random( )
Math.PI
Math.sin(0)

//Strings
var s = "hello world"
s.charAt(0)
s.charAt(s.length-2)
s.substring(1,4)
s.slice(-3)
s.lastIndexof("l")
s.replace("h","H")
s.toUpperCase()

//
var n = 18
n.toString(2) //convert by base

//parse
parseInt("2 M") //=2

//var decleration
var i = 1, j = 2, k = 3
for (var i = 0; i < 10; i++) console.log(i)

var matrix = [[1,2,3],[5,6,7],[-1,-5,-9]]

//objects
var p = { x : 2, y: 1}
var q = { }
q.xx = 123
q["xx"] === 123
"xx" in q

Math.max(1,2)

//typeof
typeof q["xx"]
typeof typeof q["xx"]