JavaScript Kit > JavaScript Reference > JavaScript Operators: Other
Other Operators
Below lists the other JavaScript Operators available.
Also See: JavaScript Operators precedence and associativity.
Other Operators
Operator | Description | ||||||||||||||||
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(,) comma | Primarily used in a for loop when you
wish to insert multiple expressions for the test conditions, the
comma (,) operator evaluates its left and right operands, and
returns the value of the right. for (var i=0,
y=0; i<5; i++, y+=2){ Output: |
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?: | The Conditional Operator (?: )
is a shorthand method for returning the result of either exp1
or exp2, depending on whether condition evaluates to
true or false. If true, the value of exp1 is returned, or if false,
the value of exp2 instead.(condition)? exp1 : exp2 For example: y=-1 |
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delete | Deletes a variable defined not
using "var ", custom object
property, method, or array element. It returns true if successful,
false if not. For example:
var myarray=['joe', 'mary', 'jane'] |
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in | The "in" operator takes an object or
array as its right operand, and a string denoting the property you
wish to search for as its left operand. Returns true if property
exists in object, false if not. var
myarray=['joe', 'mary', 'jane'] Note that properties deleted using the "delete" operator above will return false when tested for using "in". |
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instanceof | Returns a Boolean value indicating
whether the left hand operand is of the object type specified in the right
hand operand. Here object type refers to the name of the object you
wish to test for, such as Date, String, Array
etc. Use instanceof as a more clear-cut way of
detecting the type of an object or variable versus typeof . For example:var today=new Date() |
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new | Creates a new instance of a custom or
select built-in JavaScript objects such as
Date.
Only objects with a constructor function can be instantialized using
the "new " operator. The "this " keyword can
then be used anywhere inside the function to refer to the object or
object instance.var today=new Date() //create
new instance of Date object |
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try/catch/finally | Allows you to intercept exception (aka
runtime) errors in JavaScript and handle them as you see fit.
Examples of exceptions include trying to reference an undefined
variable, or calling a non existent JavaScript method. It does
not catch syntax errors (ie: forgetting to end a string with a
quotation mark). The typical set up involves a try and
catch clause to catch a possible exception, and react
accordingly if caught:try{ In the above, if " There's another clause, try{
var ajaxrequest=null Here I'm using a nested More info: "Handling runtime errors in JavaScript using try/catch/finally". |
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typeof | The "typeof" operator allows you to
probe the data type of its operand, such as whether a variable is
string, numeric, or even undefined.
Here are some of the possible return values:
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void | Evaluates a lone operand without
returning a value. Most commonly used to define JavaScript links,
where the link executes a JavaScript code instead of its default
action when clicked on. For example: <a href="javascript:void(window.open('http://google.com'))">Open Google</a> |
Example- Conditional Operator
The Conditional Operator is handy for quickly assigning a different value to a variable depending on the outcome of a condition. Here are a few examples:
var browser=(navigator.appName.indexOf("Microsoft")!=-1)? "IE" : "Non IE"
You can expand the number of possible values to assign to more than just two. In fact, there is no limit. Observe the below example, which has 3 possible values:
var browser=(navigator.appName.indexOf("Microsoft")!=-1)? "IE" : (navigator.appName.indexOf("Netscape")? "NS" : "Not IE nor NS"
In the 2nd example, "browser" will contain one of 3 possible values depending on the browser maker of the visitor.You can use a conditional operator within a larger expression, by wrapping the entire conditional operator with a parenthesis:
document.write("The total for your order is "+(onsale==true? "$25" : "$30"))
- JavaScript Operators
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