w3r-javascript05: Arithmetic Operators

Arithmetic Operators : +, -, *, /
In JavaScript, arithmetic operators take numerical values (either literals or variables) as their operands and return a single numerical value. There are four standard arithmetic operators, addition (+), subtraction (-), multiplication (*), and division (/).
These operators work as they do in other programming languages except the division (/) operator which returns a floating-point division in JavaScript, not a truncated division as it does in languages such as C or Java. For example: 1/2 returns 0.5 in JavaScript.1/2 returns 0 in Java.
In addition, JavaScript provides modules(%), increment(++), decrement(--) and unary negation(-) operators.

+ addition operator

HTML Code

<!doctype html>
<head>
<meta charset="utf-8">
<title>JavaScript + operator example</title>
<meta name="description" content="This document contains
an example of JavaScript + operator" />
</head>
<body>
<script src="addition_example1.js"></script>
</body>
</html>

JS Code

var var1 = 45;
var var2 = 78;
var var3 = 45.10;
var var4 = 178.12;
var newvar  = var1 + var2;
var newvar1 = var3 + var4;
var newParagraph3 = document.createElement("p");
var newText3 = document.createTextNode("var1 + var2 = "+newvar+" and var3 + var4 = "+newvar1);
newParagraph3.appendChild(newText3);
document.body.appendChild(newParagraph3);

- subtraction operator

HTML Code

<!doctype html>
<head>
<meta charset="utf-8">
<title>JavaScript subtraction operator example </title>
<meta name="description" content="This document contains an
example Using JavaScript subtraction operator"/>
</head>
<script src="subtraction-example1.js"></script>
</body>
</html>

JS Code

var var1 = 45;
var var2 = 78;
var str1 = "w3resource";
var str2 = ".com";
var newvar = var1 - var2;
var newstr = str1 - str2; //NAN
var varstr = var1 - str2; //NAN
var newParagraph = document.createElement("p");
var newText = document.createTextNode("var1 -var2 = "+ newvar);
newParagraph.appendChild(newText);
document.body.appendChild(newParagraph);
var newParagraph1 = document.createElement("p");
var newText1 = document.createTextNode("str1 - str2  = "+ newstr);
newParagraph1.appendChild(newText1);
document.body.appendChild(newParagraph1);
var newParagraph2 = document.createElement("p");
var newText2 = document.createTextNode("var1 - str2  = "+ varstr);
newParagraph2.appendChild(newText2);
document.body.appendChild(newParagraph2)

* multiplication operator

HTML Code

<!doctype html><head>
<meta charset="utf-8">
<title>JavaScript multiplication operator (*) example with DOM
</title>
<meta name="description" content="This document contains an example
Using JavaScript multiplication operator (*) with dom"/>
</head>
<body>
<script src="multiplication-example1.js"></script>
</body>
</html>

JS Code

var var1 = 45;
var var2 = 78;
var var3 = 45.10;
var var4 = 178.12;
var newvar  = var1 * var2;
var newvar1 = var3 * var4;

var newParagraph = document.createElement("p");
var newText = document.createTextNode("var1 * var2 = "+ newvar);
newParagraph.appendChild(newText);
document.body.appendChild(newParagraph);

var newParagraph1 = document.createElement("p");
var newText1 = document.createTextNode("var3 * var4  = "+ newvar1);
newParagraph1.appendChild newText1);
document.body.appendChild(newParagraph1);

/ division operator
HTML Code

<!doctype html>
<head>
<meta charset="utf-8">
<title>JavaScript / operator example </title>
<meta name="description" content="This document contains an example of JavaScript division operator" />
</style>
</head>
<body>
<script src="division-example1.js"></script>
</body>
</html>

JS Code

var var1 = 45;
var var2 = 78;
var var3 = 1;
var var4 = 2;
var newvar  = var1 / var2; //0.5769230769230769
var newvar1 = var3 / var4; //0.5

var newParagraph = document.createElement("p");
var newText = document.createTextNode ("var1 / var2 = "+ newvar);
newParagraph.appendChild(newText);
document.body.appendChild(newParagraph);

var newParagraph1 = document.createElement("p");
var newText1 = document.createTextNode("var3 / var4  = "+ newvar1);
newParagraph1.appendChild(newText1);
document.body.appendChild(newParagraph1);

Arithmetic Special Operators (%, ++, --, - )

Assignment Operators(+=,-=,*=,/=,%=,<<=,>>=,>>>=,&=,^=,|=)

Bitwise Operators(a & b,a | b,a ^ b,~ a,a << b,a >> b,a >>> b)

Comparison Operators(==,===,!=,!==,>,>=,<,<=)
Equal (==)
x == y Returns true if the operands are equal.

var s1 = 300;
var s2 = '300';
alert(s1==s2);//true

Strict equal (===)
x === y Returns true if the operands are equal and of the same type.

var s1 = 300,
      s2 = '300',
      s3 = 300;
alert(s1===s2);//false
alert(s1===s3);//true

Not equal (!=)
x != y Returns true if the operands are not equal.

var s1 = 300,
		s2 = '300',
		s3 = 500;
alert(s1!=s2);//false
alert(s1!=s3);//true

Strict not equal (!==)
x !== y Returns true if the operands are not equal and/or not of the same type.

var s1 = 300,
		s2 = '300',
		s3 = 500;
alert(s1!==s2);//true
alert(s1!==s3);//true

Greater than (>)
Greater than or equal (>=)

Less than (<)
Less than or equal (<=)

Logical Operators(&&, ||, !)

String Concatenation(+, +=)

Special Operators:

?: (Conditional operator)
Condition ? expr1 : expr2
status = (marks >= 30) ? "Pass" : "Fail"

Comma Operator
The comma operator (,) is used to execute two expressions sequentially.

expr1, expr2

We use the comma operator when we want to include multiple expressions in a location that requires a single expression.
This operator is generally used inside a for loop, to allow multiple variables to be updated (increase/decrease) each time through the loop.
For example we want to display a serial No. (starting from 1) and a employee code ( starting from 10 ), the following code uses the comma operator to increment two variables at once.

for (var i=1, j=10; i <=10; i++, j++)
{
alert('Sl. No. : '+i+' Employee Code : '+j)
}

function Operator
The function operator defines a function inside an expression.
var1 = function( parameter1, parameter2,......parametern)

{
statement(s)
}

var a = 12;
var b = 14;
var x = function(a,b)
{
return a*a+2*a*b+b*b;
};
alert("The square of "+a+ " and "+b +" is " +x(a,b));

in Operator

property in object
어떤 속성 이 대상 에 존재 하 는 지 판단 합 니 다.
property : Name of the property.
object : Name of the object.

var employeeobj = {name:"Robert",designation:"Officer",age:"34"};
if ("designation" in employeeobj)
{
alert('Designation property is present'); //alert this
}
else
{
alert('Designation property is not present'); 
}

instanceof Operator
The instanceof operator is used to check the type of an object at run time. The instanceof operator returns a boolean value that indicates if an object is an instance of a particular class.

var result = objectName instanceof objectType

var string1 = "w3resource"; //Declaring string object
var date1 = new Date();  //Declaring Date object
if (string1 instanceof String) 
{
var newParagraph = document.createElement("p");
var newText = document.createTextNode('The type of string1 object is String'); 
newParagraph.appendChild(newText);
document.body.appendChild(newParagraph); 
}
if (date1 instanceof Date)
{
var newParagraph1 = document.createElement("p");
var newText1 = document.createTextNode('The type of date1 object is Date'); 
newParagraph1.appendChild(newText1);
document.body.appendChild(newParagraph1);
}

new Operator
The new operator is used to create an instance of a user defined object type or one of builtin object types which has a constructor function.

var objectName = new objectType(param1, param2, ...., paramN);

To create an user defined object type following steps are required.
Write a function to define the object type 대상 형식 을 정의 하기 위해 함 수 를 쓰 십시오.
Use new operator to create an instance of the object. new 연산 자 를 사용 하여 이 대상 의 인 스 턴 스 를 만 듭 니 다.

Suppose we want to create an object type for students with three properties name, class and rollno. To do this first declare the following function.

  function student(name, class, rollno)
    { 
    this.name = name;
    this.class = class 
    this.rollno = rollno;
    }

new 키 워드 를 사용 하여 대상 생 성 완료

studentv = new student("John", "V", 10)

studentvi = new student("David Rayy", "VI", 12)

  function school(sname,  city, stus)
    { 
    this.sname = sname;
    this.city = city;
    this.stus = stus;
    }

var stus = new Array(studentv,studentvi);

school = new school("Dubai International School", "Dubai", stus);

this Operator
The this operator is used to refer the current object. In general, this refers to the calling object in a method.
In the following web document this operator is used as internal reference property of the form instances.

<!doctype html>
<head>
<meta charset="utf-8">
<title>JavaScript this operator example with DOM
</title>
<meta name="description" content="This document contains an
example of JavaScript this operator"/>
</head>
<body>
<form name="myform" action="#">
<input type="text" value="Text Here" name="text1" />
<input type= "submit" value="Submit" name="mysubmit" onclick=
"formdetails(this.form)" />
</form>
<script src="javascript-this-operator-example1.js">
</script>
</body>
</html>

 //this ---> form
function formdetails(form)
{

var newParagraph = document.createElement("p"); 
var newText = document.createTextNode("The name of the form is: "+form.name); 
newParagraph.appendChild(newText); 
document.body.appendChild(newParagraph);


var newParagraph1 = document.createElement("p"); 
var newText1 = document.createTextNode("The
deault value of text box is: "+form.text1.value);  newParagraph1.appendChild(newText1); 
document.body.appendChild(newParagraph1);


var newParagraph2 = document.createElement("p");
var newText2 = document.createTextNode("The name
of the submit button box is: "+form.mysubmit.name); newParagraph2.appendChild(newText2);
document.body.appendChild(newParagraph2);

var newParagraph3 = document.createElement("p"); 
var newText3 = document.createTextNode("The deault
value of submit button is: "+form.mysubmit.value);
newParagraph3.appendChild(newText3);
document.body.appendChild(newParagraph3);

}

typeof operator
The typeof operator is used to get the data type (returns a string) of its operand.
The operand can be either a literal or a data structure such as a variable, a function, or an object. The operator returns the data type.

반환 값: 문자열
"object"，"boolean"，"function"，"number"，"string"，"undefined"

Examples of typeof operator : string

typeof ""
typeof "abc"
typeof (typeof 1)

Examples of typeof operator : number

typeof 17
typeof -14.56
typeof 4E-3
typeof Infinity
typeof Math.LN2
typeof NaN

Examples of typeof operator : boolean

typeof false
typeof true

Examples of typeof operator : function

typeof Math.tan
typeof function(){}

Examples of typeof operator : object

typeof {a:1}
typeof new Date()
typeof null
typeof /a-z/
typeof Math
typeof JSON

Examples of typeof operator : undefined

typeof undefined
typeof abc

More examples on typeof operator

typeof(4+7); //returns number typeof("4"+"7"); //returns string typeof(4*"7"); //returns number
typeof(4+"7"); //returns string

What is the difference between typeof myvar and typeof(myvar) in JavaScript?
No difference!

How to detect an undefined object property in JavaScript?

var index = 8;
  var result = (typeof index === 'number');
  alert(result);
  // Output: true
var description = "w3resource";
  var result = (typeof description === 'string');
  alert(result); 
  // Output: true

void operator
The void operator is used to evaluate a JavaScript expression without returning a value.

The following web document shows how the void operator is used.

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset=utf-8>
<title>JavaScript void operator example</title>
</head>
<body>
<a href="javascript:void(alert('Thank you.'))">Click here to see a message</a>
</body>
</html>

In the following web document void operator is used to call a function.

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset=utf-8>
<title>JavaScript void operator (calling function) example</title>
</head>
<body>
<script type="text/javascript">
function testfunc(){document.write("good!");}
</script>
<a href="javascript:void(testfunc())">
Click here to call testfunc()</a>
</body>
</html>

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w3r-javascript05: Arithmetic Operators

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