Web Technology Experts Notes

Wednesday, 20 January 2016

jQuery UI Interview Questions and Answers

Question: What is jQuery UI? It is JavaScript Library which is collection of jQuery widgets like datepicker, tabs, autocomplete etc. We can also add effects, interactions (drag, drop, resize) on widgets.

Question: What widets are available in jQuery UI?

Accordion
Autocomplete
Button
Datepicker
Dialog
Menu
Progressbar
Selectmenu
Slider
Spinner
Tabs
Tooltip

Question: What are different effects available in jQuery UI

Add Class
Color Animation
Easing
Effect
Hide
Remove Class
Show
Switch Class
Toggle
Toggle Class

Question: In which language, JQuery UI is written?
JavaScript

Question: Is JQuery UI opensource?
Yes.
Question: What is current stable version of JQuery UI?
1.11.4 / dated 11 March 2015

Question: From where we can download the jQuery UI
https://jqueryui.com/

Question: Can we download custom widgets from jQuery UI
Yes, We can.
https://jqueryui.com/download/

Question: How to add CSS property on last div?

$('div:last').css({backgroundColor: 'green', fontWeight: 'bolder'});

Question: What is $.noConflict()?

<script src="https://code.jquery.com/jquery-1.6.2.js" type="text/javascript"></script>
<script type="text/javascript">
$.noConflict()
</script>

When we call to $.noConflict(). Old references of $ are saved during jQuery initialization, noConflict() simply restores them.

Question: Can we use another variable instead of $ in jQuery? If yes, How?
Yes, we can.

var jQ = jQuery.noConflict();
/** Now use jQ instead of $ **/
jQ( "div#pid" ).hide();

Question: How to remove close button on the jQuery UI dialog using CSS?

.ui-dialog-titlebar-close {
  visibility: hidden;
}

Question: How to remove close button on the jQuery UI dialog using JavaScript?

$("#div2").dialog({
   closeOnEscape: false,
   open: function(event, ui) { $(".ui-dialog-titlebar-close", ui.dialog | ui).hide(); }
});

Question: How to initialize a dialog without a title bar?

var dialogOpts=[]
$("#divId").dialog(dialogOpts);
//Remove the title bar
$(".ui-dialog-titlebar").hide();

Question: How to call Hook into dialog close event in jQuery UI?

$('div#contentId').on('dialogclose', function(event) {
     //console.log('closed event called');
 });

Question: How to Download jQuery UI CSS from Google's CDN?
Uncompressed: http://ajax.googleapis.com/ajax/libs/jqueryui/1.10.3/jquery-ui.js
Compressed: http://ajax.googleapis.com/ajax/libs/jqueryui/1.10.3/jquery-ui.min.js

Question: How to "Change button text" in JQuery?
jQuery Version < 1.6

$("#elementId").attr('value', 'Save'); //versions older than 1.6

jQuery Version > 1.6

$("#elementId").prop('value', 'Save'); //versions newer than 1.6

Question: How can I disable a button in a jQuery ?

$('#divId').attr("disabled", true);

Question: How do I keep jQuery UI Accordion collapsed by default?

$("#divId").accordion({ header: "h4", collapsible: true, active: false });

Question: How to call a dragable widget?

// Make #draggable draggable
$(function () {
        $("#draggableDivId").draggable();
});

Question: How do I disable a jquery-ui draggable of widget?

//myObject is widget object.
myObject.draggable( 'disable' );

OR, you can set during the initalization

$("#yourDialogId").dialog({
    draggable: false
});

How to remove JQuery UI Autocomplete Helper text?

.ui-helper-hidden-accessible { display:none; }

Question: How to set year in DatePicker?

 $(".datepickerClass").datepicker({
    yearRange: '1950:2013', 
   changeMonth: true,
   changeYear: true,
   showButtonPanel: true,
   
});

Question: How to set current Date in Date Picker?

$(".datepickerClass").datepicker('setDate', new Date());

Question: How to Change Date Format in jQuery UI DatePicker?

var date = $('#datepickerDivId').datepicker({ dateFormat: 'dd-mm-yy' }).val();

Tuesday, 19 January 2016

PHP 7 new features

Following are PHP 7 new features

Scalar type declarations: In this we can declare what type of argument will be accepted by functions.

function sumOfInts(int ...$all_ints){ /** It will accept only integers **/
    return array_sum($all_ints);
}
echo sumOfInts(2, 3); //5
echo sumOfInts(2, '3', '5'); //10
echo sumOfInts(2, '3', 'string'); //Error: Uncaught TypeError: Argument 3 passed to sumOfInts() must be of the type integer, string given

Return type declarations : In this we can declare what what will be the datatype from functions.
```
function sumOfInts(int ...$all_ints):int
{
    return array_sum($all_ints);
}
echo sumOfInts(2, 3); //5
echo sumOfInts(2, '3', '5'); //10
```
Here if function "sumOfInts" return an string OR Array, it will give error.

Null coalescing operator (??) have been added.

$userId = $_GET['user_id'] ?? '0';

is equivalent to

$userId = isset($_GET['user_id']) ? $_GET['user_id'] : '0';

Spaceship operator :The spaceship operator is used for comparing two expressions. It returns -1, 0 or 1
```
echo 1 <=> 1; // 0
echo 1 <=> 2; // -1
echo 2 <=> 1; // 1
```

define() updates: Now you can add array.

define('CLIENTS', [
    'client 1',
    'client 2',
    'client 3'
]);

echo CLIENTS[1];//client 2

Unicode codepoint escape syntax
```
echo "\u{aa}";
echo "\u{9999}";
```

Closure::call Temporarily binding an object scope to a closure and invoking it.

class A {private $x = 1;}
$getX = function() {return $this->x;};
echo $getX->call(new A);

unserialize updates: Provide better security when unserializing objects on untrusted data and prevents possible code injections by enabling the developer to whitelist classes that can be unserialized.
```
$data = unserialize($searilizedData, ["allowed_classes" => ["MyClass", "MyClass2"]]);
```
list() function updates: Now list() can unpack the object also. Earlier it unpack int, float, string and array only.
session_start() function updates:
Now you can pass array-options in this function. For Example:
```
session_start([
    'cache_limiter' => 'private',
    'read_and_close' => true,
]);
```
intdiv() new function It performs an integer division of its operands and returns it. For Example:
```
echo intdiv(100, 3); //33
```
use updations Classes, functions and constants being imported from the same namespace can now be grouped together in a single use statement Below both are Same.
```
use some\namespace\ClassA;
use some\namespace\ClassB;
use some\namespace\ClassC as C;
```
OR
```
use some\namespace\{ClassA, ClassB, ClassC as C};
```

CSPRNG Functions i.e. random_bytes() and random_int()

$bytes = random_bytes(5);
var_dump(bin2hex($bytes)); //string(10) "385e33f741"
var_dump(random_int(1, 100));//1-100

Generator delegation: Generators can now delegate to another generator using yield, Traversable object/array automatically.

function func1()
{
    yield 1;
    yield 2;
    yield from func2();
}

function func2()
{
    yield 3;
    yield 4;
}

foreach (func1() as $val)
{
    echo $val, PHP_EOL;
}
/** Output 
1
2
3
4
Output **/