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![Declare + Initialize Arrays
var array_name = [“a” , ”b” , ”c”];
Using the JavaScript Keyword new](https://cdn.statically.io/img/image.slidesharecdn.com/javascriptarrays-141202114627-conversion-gate01/75/Javascript-arrays-6-2048.jpg)
![Associative Array
(keys and values) var person = [];
person [“ firstName "] = “Hassan";
person [“ lastName "] = "Dar";
OR](https://cdn.statically.io/img/image.slidesharecdn.com/javascriptarrays-141202114627-conversion-gate01/75/Javascript-arrays-8-2048.jpg)
![Indexing Array
Array elements are accessed using their index number:
var ary = [“A” , “B” , “C” , “D” , “E” , “F”];
document.write(ary[4]); //output : E](https://cdn.statically.io/img/image.slidesharecdn.com/javascriptarrays-141202114627-conversion-gate01/75/Javascript-arrays-9-2048.jpg)
![Deleting Elements
delete array[number]
• Removes the element, but leaves
a hole in the numbering.
array.splice(number, 1)
• Removes the element and
renumbers all the following
elements.](https://cdn.statically.io/img/image.slidesharecdn.com/javascriptarrays-141202114627-conversion-gate01/75/Javascript-arrays-31-2048.jpg)
![Deleting Elements
Ary = ['a', 'b', 'c', 'd‘ ,‘e’];
delete Ary[1];
['a',undefined, 'c', 'd‘ ,’e’]](https://cdn.statically.io/img/image.slidesharecdn.com/javascriptarrays-141202114627-conversion-gate01/75/Javascript-arrays-32-2048.jpg)
Uploaded byHassan Dar
Javascript arrays
This document provides an overview of JavaScript arrays, including: - Declaring and initializing different types of arrays such as associative arrays and indexed arrays - Common array methods like push(), pop(), splice(), and slice() - Array attributes including length, indexOf, and typeOf - Techniques for adding, removing, and modifying array elements
Javascript arrays
- 1.
- 2. Group Members •M.Tayyab • Hassan Dar • Saddam Butt • Bilal Khan
- 3. TOPICS • Arrays • Declaring and Allocating Array • Types of Array • Array Methods • Array Attributes
- 4. Arrays • Arrayinherits from Object. • Indexes are converted to strings and used as names for retrieving values. • Very efficient for sparse arrays. • Not very efficient in most other cases. • One advantage: No need to provide a length or type when creating an array.
- 5. Declaring and AllocatingArrays • JavaScript arrays are Array objects. • Creating new objects using the new operator is known as creating an instance or instantiating an object • Operator new is known as the dynamic memory allocation operator
- 6. Declare + InitializeArrays var array_name = [“a” , ”b” , ”c”]; Using the JavaScript Keyword new
- 7. Types of Array • Associative Array • Index Array
- 8. Associative Array (keysand values) var person = []; person [“ firstName "] = “Hassan"; person [“ lastName "] = "Dar"; OR
- 9. Indexing Array Arrayelements are accessed using their index number: var ary = [“A” , “B” , “C” , “D” , “E” , “F”]; document.write(ary[4]); //output : E
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- 11. Array Methods •Concat • Join • Push • Pop • UnShift • Shift • Sort • Slice • Splice
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- 13. Join The join()method also joins all array elements into a string. It behaves just like toString(), but you can specify the separator:
- 14. PUSH The push()method adds a new element to an array (at the end):
- 15. POP The pop()method removes the last element from an array:
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- 22. SPLICE The splice()method can be used to add new items to an array and also Remove items from Array: Add Values
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- 25. Array Attributes •length •indexOf •typeOf M •Changing Elements •Deleting Elements
- 26. LENGTH….. • Thelength property provides an easy way to append new elements to an array without using the push() method.
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- 29. Typeof A commonquestion is: How do I know if a variable is an array? The problem is that the JavaScript operator typeof returns "object":
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- 31. Deleting Elements deletearray[number] • Removes the element, but leaves a hole in the numbering. array.splice(number, 1) • Removes the element and renumbers all the following elements.
- 32. Deleting Elements Ary= ['a', 'b', 'c', 'd‘ ,‘e’]; delete Ary[1]; ['a',undefined, 'c', 'd‘ ,’e’]
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