Types, Operators and Primitives

JavaScript Training

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Data Types, Operators and Primitives

Undefined undefined Null null Boolean true String "hello" Number 2 Object {name: "value"} Array [1,2,3] Date new Date() RegExp /.*/g, Function function(){}

Data Types

Primitive

Object

varnewassignment

deletemember

call

comparison

Operators

var foonew Foofoo = {bar: "a value"}foo.bar = valuedelete foo.barfoo.barfoo["bar"]bar()foo.bar()=====

var me = { name: {first: "justin"} },

name = me.name;

name = {first: "alexis"};

me.name.first // justin

WINDOWAddress Value

…. ….

x1001

x1002

x1003

x1004

…. ….

x2001

x2002

x2003

x2004

var str = "hi";

var str = "hi";

Address Value

…. ….

x1001 call-object

x1002

x1003

x1004

…. ….

x2001

x2002

x2003

x2004

WINDOW

"hi"

Address Value

…. ….

x1001 call-object

x1002

x1003

x1004

…. ….

x2001 STRING

x2002 2

x2003 hi

x2004

"hi"

WINDOW

var str = "hi";

Address Value

…. ….

x1001 call-object

x1002

x1003

x1004

…. ….

x2001 STRING

x2002 2

x2003 hi

x2004

str "hi"

WINDOW

var str = "hi";

"hi"str

Address Value

…. ….

x1001 call-object

x1002 str

x1003 -----

x1004

…. ….

x2001 STRING

x2002 2

x2003 hi

x2004

WINDOW

var str = "hi";

var str = "hi";

Address Value

…. ….

x1001 call-object

x1002 str

x1003 2001

x1004

…. ….

x2001 STRING

x2002 2

x2003 hi

x2004

"hi"str

WINDOW

var obj = {};obj.txt = "hi";

Address Value

…. ….

x1001

x1002

x1003

…. ….

x2001

x2002

x2003

x2004

…. ….

x2101

x2102

x2103

WINDOW

var obj = {};obj.txt = "hi";

Address Value

…. ….

x1001 call-object

x1002

x1003

…. ….

x2001

x2002

x2003

x2004

…. ….

x2101

x2102

x2103

WINDOW

var obj = {};obj.txt = "hi";

Address Value

…. ….

x1001 call-object

x1002

x1003

…. ….

x2001 OBJECT

x2002 0

x2003

x2004

…. ….

x2101

x2102

x2103

WINDOW

var obj = {};obj.txt = "hi";

Address Value

…. ….

x1001 call-object

x1002 obj

x1003 -----

…. ….

x2001 OBJECT

x2002 0

x2003

x2004

…. ….

x2101

x2102

x2103

obj

WINDOW

var obj = {};obj.txt = "hi";

Address Value

…. ….

x1001 call-object

x1002 obj

x1003 -----

…. ….

x2001 OBJECT

x2002 0

x2003

x2004

…. ….

x2101

x2102

x2103

obj

WINDOW

var obj = {};obj.txt = "hi";

Address Value

…. ….

x1001 call-object

x1002 obj

x1003 x2001

…. ….

x2001 OBJECT

x2002 0

x2003

x2004

…. ….

x2101

x2102

x2103

"hi"

obj

WINDOW

var obj = {};obj.txt = "hi";

Address Value

…. ….

x1001 call-object

x1002 obj

x1003 x2001

…. ….

x2001 OBJECT

x2002 0

x2003

x2004

…. ….

x2101 STRING

x2102 2

x2103 hi

"hi"

obj

txt

WINDOW

var obj = {};obj.txt = "hi";

"hi"

obj

txt

Address Value

…. ….

x1001 call-object

x1002 obj

x1003 x2001

…. ….

x2001 OBJECT

x2002 1

x2003 txt

x2004 x2101

…. ….

x2101 STRING

x2102 2

x2103 hi

WINDOW

delete

var me = { name: { first:"justin" } }, name = me.name;

delete me.name;

name.first //-> "Justin"

WINDOW

name

name

"justin"

me

first

typeof

Type Result

Undefined "undefined"

Null "object"

Boolean "boolean"

Number "number"

NaN "number"

String "string"

Function "function"

Array "object"

Any other object

"object"

Summary

Variables are put in a call object.

var me;

= sets a variable or property to point somewhere in memory.

me = {};me.age = 30;

WINDOW

me

30

age

var me = { name: { first:"justin" } }, name = me.name;

name = { first:"alexis"};

me.name.first

Understanding

WINDOW

name

"alexis"first

name

"justin"

me

first

var me = { name: { first:"justin" } }, name = me.name;

name = { first:"alexis"};

me.name.first

Understanding

WINDOW

name

"alexis"first

name

"justin"

me

first