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Thursday, 19 November 2015

Top 10 jQuery interview Questions and Answers

Top 10 jQuery interview Questions and Answers


Question: How to replace the text of div using class?
Suppose HTML
<div class="myDivClass">
Update this text</div>
jQuery code 
$('.myDivClass').text('Updated'); 



Question: How to replace the text of div using "div id"?
Suppose HTML
<div id="myDivId">
Update this text</div>
jQuery code 
$('#myDivId').text('Updated'); 



Question: How to replace the html of div using class?
Suppose HTML
<div class="myDivClass">
Update this html</div>
jQuery code 
$('.myDivClass').html('Updated'); 



Question: How to replace the text of div using "div id"?
Suppose HTML
<div id="myDivId">
Update this text</div>
jQuery code 
$('#myDivId').html('Updated'); 



Question: How to Check if checkbox is checked?
Suppose HTML is
<input name="lang[]" type="checkbox" value="English" />
<input name="lang[]" type="checkbox" value="Hindi" />
<input name="lang[]" type="checkbox" value="Urdu" />

JQuery code
var totalCheckboxSelected = $('input[name="lang[]"]:checked').length;
if(totalCheckboxSelected){
    console.log(totalCheckboxSelected+' check box checked');
}else{
    console.log('NO checkbox is selected');
}



Question: How can you check for a #hash in a URL?
if(window.location.hash) {
    var hashValue = window.location.hash.substring(1);
    console.log(hashValue);
} else {
  console.log('Hash not found');
} 



Question: How get to know which mouse button is pressed?
$('#divId').mousedown(function(event) {
    switch (event.which) {
        case 1:
            console.log('Left button pressed.');
            break;
        case 2:
            console.log('Middle button pressed.');
            break;
        case 3:
            console.log('Right button pressed.');
            break;
        default:
            console.log('Exception Case!');
    }
});



Question: How to add update the color of div with jQuery?
$('div#divId').css("background-color", "red");



Question: How to remove class from div?
$("div#divId").removeClass('className'); 



Question: How do I get the value of a textbox using jQuery?
Html

<input id="websiteId" name="website" type="text" value="Web Technology Experts Notes" /> jQuery:
$("#websiteId").val();



Question: How to submit form with post method with Ajax?
HTML Form
<form action="/ajax/form-url" id="ajaxform" method="POST" name="ajaxform">
First Name: <input name="fname" type="text" value="" /> <br />
Last Name: <input name="lname" type="text" value="" /> <br />
<input name="submit" type="submit" value="Submit the Form" /> </form>

jQuery Code
$( document ).ready(function() {
    $("#ajaxformSubmit").submit(function(e)
    {
        var postData = $(this).serializeArray();
        var formURL = '/ajax/form-url'
        $.ajax(
        {
            url : formURL,
            type: "POST",
            data : postData,
            success:function(data, textStatus) 
            {            console.log(data);
            }
        });
        e.preventDefault(); //STOP default action
    });
});



Question: How to escape the text?
var someHtmlString = "";
var escaped = $("
").text(someHtmlString).html(); console.log(escaped); //<script>aalert('hi!');</script>



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