What is the use of Void(0)?
Void(0) is used to prevent the page from refreshing and parameter “zero” is passed while calling.
Void(0) is used to call another method without refreshing the page.
How can a page be forced to load another page in JavaScript?
The following code has to be inserted to achieve the desired effect:
<script language="JavaScript" type="text/javascript" >
<!-- location.href="http://newhost/newpath/newfile.html"; //--></script>
What is the data type of variables of in JavaScript?
All variables in the JavaScript are object data types.
What is the difference between an alert box and a confirmation box?
An alert box displays only one button which is the OK button.
But a Confirmation box displays two buttons namely OK and cancel.
What are escape characters?
Escape characters (Backslash) is used when working with special characters like single quotes, double quotes, apostrophes and ampersands. Place backslash before the characters to make it display.
Example:
document.write "I m a "good" boy"
document.write "I m a \"good\" boy"
What are JavaScript Cookies?
Cookies are the small test files stored in a computer and it gets created when the user visits the websites to store information that they need. Example could be User Name details and shopping cart information from the previous visits.
What is the difference between proxied and proxyless calls in AJAX?
Proxied calls are made through stub objects which can be called from PHP classes on the JavaScript side in AJAX.
Proxyless calls are made using utility JavaScript functions like HTML_AJAX.replace() and HTML_AJAX.append() in AJAX.
What are the protocols used by Ajax?
HTTP’s GET or POST
XMLHttpRequest for placing a request with the web server
Uses JSON to communicate between the client and server
UED or URL encoded data
What are all the security issues of Ajax?
Security issues that can be encountered
When Ajax calls are sent through plain text and it may lead to know the database details
Inserting scripts can also be possible and attackers can easily penetrate into the system
How can we handle concurrent requests?
Javascript functions should be written to handle concurrent requests and call back function can be passed as a parameter. Those parameters are passed to AjaxInteraction(URL, callback) object.
Define the role of the Update Panel?
Update Panel is used to add functionality to the existing ASP.NET applications. By using partial page rendering, it can be used to update the content. Refresh can be made for the partial page instead of whole page.
Can we use nested update panel in Ajax?
Yes, we can use nested update panel in Ajax. Update panels can be nested to have more control over the Page Refresh.
What is the difference between JavaScript and Jscript?
Both are almost similar. JavaScript is developed by Netscape and Jscript was developed by Microsoft .
How are object properties assigned?
Properties are assigned to objects in the following way –
obj["class"] = 12;
or
obj.class = 12;
What is the ‘Strict’ mode in JavaScript and how can it be enabled?
Strict Mode adds certain compulsions to JavaScript. Under the strict mode, JavaScript shows errors for a piece of codes, which did not show an error before, but might be problematic and potentially unsafe. Strict mode also solves some mistakes that hamper the JavaScript engines to work efficiently.
Strict mode can be enabled by adding the string literal “use strict” above the file. This can be illustrated by the given example:
function myfunction()
{
“use strict";
var v = “This is a strict mode function";
}
What is the way to get the status of a CheckBox?
The status can be acquired as follows –
alert(document.getElementById(‘checkbox1′).checked);
If the CheckBox will be checked, this alert will return TRUE.
How can the OS of the client machine be detected?
The navigator.appVersion string can be used to detect the operating system on the client machine.
Explain window.onload and onDocumentReady?
The onload function is not run until all the information on the page is loaded. This leads to a substantial delay before any code is executed.
onDocumentReady loads the code just after the DOM is loaded. This allows early manipulation of the code.
How will you explain closures in JavaScript? When are they used?
Closure is a locally declared variable related to a function which stays in memory when the function has returned.
For example:
function greet(message) {
console.log(message);
}
function greeter(name, age) {
return name + " says howdy!! He is " + age + " years old";
}
// Generate the message
var message = greeter("James", 23);
// Pass it explicitly to greet
greet(message);
This function can be better represented by using closures
function greeter(name, age) {
var message = name + " says howdy!! He is " + age + " years old";
return function greet() {
console.log(message);
};
}
// Generate the closure
var JamesGreeter = greeter("James", 23);
// Use the closure
JamesGreeter();
How can a value be appended to an array?
A value can be appended to an array in the given manner –
arr[arr.length] = value;
Explain the for-in loop?
The for-in loop is used to loop through the properties of an object.
The syntax for the for-in loop is –
for (variable name in object){
statement or block to execute
}
In each repetition, one property from the object is associated to the variable name, and the loop is continued till all the properties of the object are depleted.
Describe the properties of an anonymous function in JavaScript?
A function that is declared without any named identifier is known as an anonymous function. In general, an anonymous function is inaccessible after its declaration.
Anonymous function declaration –
var anon = function() {
alert('I am anonymous');
};
anon();
Void(0) is used to prevent the page from refreshing and parameter “zero” is passed while calling.
Void(0) is used to call another method without refreshing the page.
How can a page be forced to load another page in JavaScript?
The following code has to be inserted to achieve the desired effect:
<script language="JavaScript" type="text/javascript" >
<!-- location.href="http://newhost/newpath/newfile.html"; //--></script>
What is the data type of variables of in JavaScript?
All variables in the JavaScript are object data types.
What is the difference between an alert box and a confirmation box?
An alert box displays only one button which is the OK button.
But a Confirmation box displays two buttons namely OK and cancel.
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| Mphasis JavaScript Most Frequently Asked Latest Interview Questions Answers |
What are escape characters?
Escape characters (Backslash) is used when working with special characters like single quotes, double quotes, apostrophes and ampersands. Place backslash before the characters to make it display.
Example:
document.write "I m a "good" boy"
document.write "I m a \"good\" boy"
What are JavaScript Cookies?
Cookies are the small test files stored in a computer and it gets created when the user visits the websites to store information that they need. Example could be User Name details and shopping cart information from the previous visits.
What is the difference between proxied and proxyless calls in AJAX?
Proxied calls are made through stub objects which can be called from PHP classes on the JavaScript side in AJAX.
Proxyless calls are made using utility JavaScript functions like HTML_AJAX.replace() and HTML_AJAX.append() in AJAX.
What are the protocols used by Ajax?
HTTP’s GET or POST
XMLHttpRequest for placing a request with the web server
Uses JSON to communicate between the client and server
UED or URL encoded data
What are all the security issues of Ajax?
Security issues that can be encountered
When Ajax calls are sent through plain text and it may lead to know the database details
Inserting scripts can also be possible and attackers can easily penetrate into the system
How can we handle concurrent requests?
Javascript functions should be written to handle concurrent requests and call back function can be passed as a parameter. Those parameters are passed to AjaxInteraction(URL, callback) object.
Define the role of the Update Panel?
Update Panel is used to add functionality to the existing ASP.NET applications. By using partial page rendering, it can be used to update the content. Refresh can be made for the partial page instead of whole page.
Can we use nested update panel in Ajax?
Yes, we can use nested update panel in Ajax. Update panels can be nested to have more control over the Page Refresh.
What is the difference between JavaScript and Jscript?
Both are almost similar. JavaScript is developed by Netscape and Jscript was developed by Microsoft .
How are object properties assigned?
Properties are assigned to objects in the following way –
obj["class"] = 12;
or
obj.class = 12;
What is the ‘Strict’ mode in JavaScript and how can it be enabled?
Strict Mode adds certain compulsions to JavaScript. Under the strict mode, JavaScript shows errors for a piece of codes, which did not show an error before, but might be problematic and potentially unsafe. Strict mode also solves some mistakes that hamper the JavaScript engines to work efficiently.
Strict mode can be enabled by adding the string literal “use strict” above the file. This can be illustrated by the given example:
function myfunction()
{
“use strict";
var v = “This is a strict mode function";
}
What is the way to get the status of a CheckBox?
The status can be acquired as follows –
alert(document.getElementById(‘checkbox1′).checked);
If the CheckBox will be checked, this alert will return TRUE.
How can the OS of the client machine be detected?
The navigator.appVersion string can be used to detect the operating system on the client machine.
Explain window.onload and onDocumentReady?
The onload function is not run until all the information on the page is loaded. This leads to a substantial delay before any code is executed.
onDocumentReady loads the code just after the DOM is loaded. This allows early manipulation of the code.
How will you explain closures in JavaScript? When are they used?
Closure is a locally declared variable related to a function which stays in memory when the function has returned.
For example:
function greet(message) {
console.log(message);
}
function greeter(name, age) {
return name + " says howdy!! He is " + age + " years old";
}
// Generate the message
var message = greeter("James", 23);
// Pass it explicitly to greet
greet(message);
This function can be better represented by using closures
function greeter(name, age) {
var message = name + " says howdy!! He is " + age + " years old";
return function greet() {
console.log(message);
};
}
// Generate the closure
var JamesGreeter = greeter("James", 23);
// Use the closure
JamesGreeter();
How can a value be appended to an array?
A value can be appended to an array in the given manner –
arr[arr.length] = value;
Explain the for-in loop?
The for-in loop is used to loop through the properties of an object.
The syntax for the for-in loop is –
for (variable name in object){
statement or block to execute
}
In each repetition, one property from the object is associated to the variable name, and the loop is continued till all the properties of the object are depleted.
Describe the properties of an anonymous function in JavaScript?
A function that is declared without any named identifier is known as an anonymous function. In general, an anonymous function is inaccessible after its declaration.
Anonymous function declaration –
var anon = function() {
alert('I am anonymous');
};
anon();