JQuery Interview Questions Part - 8

JQuery Interview Questions Part - 8

Q 1.     What are JQuery utilities?

Ans 1. JQuery provides several utility methods that are helpful in completing the desired programming tasks

Example –

Suppose, I have a string -  “     Hello       ” but I need the text “Hello” without any spaces on its left or right, then I can use trim() JQuery utility to remove any such spaces.

Q 2.     How to use JQuery trim utility method?

Ans 2. $.trim() is used to remove the leading and trailing whitespace.

Example –

$.trim(“     Hello       ”) will return “Hello”

Q 3.    How to use JQuery each utility method?

Ans 3. $.each() is used to iterate over arrays and objects. It can work on arrays and objects.

Example –

Usage with arrays –

$.each([“JQuery”, “Javascript”, “AngularJS”], function( index, value){

        alert(“Element at index: ” + index + “ is ” + value);

});

Result-

Element at index: 0 is JQuery

Element at index: 1 is Javascript

Element at index: 2 is AngularJS

Usage with Objects -

$.each({Library: “JQuery”, Framework: “AngularJS”}, function(key, value){

        alert(“Key: ” + key + “ value: ” + value);

});

Result-

Key: Library value: JQuery

Key: Framework value: AngularJS

Q 4.     How to use JQuery inArray utility method?

Ans 4. $.inArray() is used to Returns a value's index in an array, or -1 if the value is not in the array.

Example -

var testArray = [“JQuery”, “Javascript”,  “AngularJS”];

var returnedValue = $.inArray(“C++”, testArray);

alert(returnedValue);

Result: -1 (Because C++ does not exist in the array)

If “C++” is replaced with “AngularJS” in the above statement, then result will be: 2

Q 5.     How to use JQuery extend utility method?

Ans 5. $.extend() is used to change the properties of the first object using the properties of subsequent objects.

EXAMPLE –

var testObject1 = { Language: “C#”, Library: “JQuery”};

var testObject2 = { Language: “Java”, Library: “JQuery”};

var testObject3 = $.extend( testObject1, testObject2);

alert(testObject1.Language);

Result – C#

alert(testObject3.Language);

Result - Java

Q 6.     How to use JQuery proxy utility method?

Ans 6. $.proxy() is used to return a function that will always run in the provided scope i.e. it relates a general function to a specific object.

EXAMPLE –

var testFunction = function(){

alert(this);
}

var testObject = {Library: “JQuery”, Language: “C#”};

testFunction();

Result: [object Window]

var proxy = $.proxy(testFunction, testObject);

proxy();

Result: [object Object]

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