Common operations on JavaScript arrays

1. Creating an array
just declares the array and does not contain specific data.
Java code
var checkboxlist = new array();

Create an array and specify the length. This length of 5 can be changed and can grow automatically.
Java code
var checkboxlist = new array(5);

Create an array and initialize three elements.
Java code
var checkboxlist = new array("1111", "2222", "3333");

2. Array operation
2.1 push() Add an element to the end of the array and return the latest length of the array

Change the string "userid001 "Put it at the end of the array
Java code
checkboxlist.push("userid001");

Add two elements at a time, "aaaa" and "bbbb"
Java code
checkboxlist.push("aaaa", "bbbb");

2.2 unshift() Insert elements at the beginning of the array, and move the original elements backward
Insert two elements at the beginning of the array.
(Some information says that the return value is the latest length of the array, but I tested the return value in ie6 to be "undefined")
Java code
checkboxlist.unshift("aaaa","bbbb");

2.3 pop() removes the end of the array an element and returns that element.
Code:
Java code
checkboxlist.pop();

2.3 shift() removes an element at the beginning of the array and returns the element
Code:
Java code
checkboxlist.shift()

2.4 splice() insert ( Replace) or remove multiple elements
Example of removal:
splice(delindex,delcount);
delindex: The position to start removing, which is the subscript of the array, starting from 0.
delcount: The number of elements removed.
Start from the first element of the array and remove 2 elements.
Java code
checkboxlist.splice(0,2);

For example: after executing checkboxlist.splice(1,2), the array changed from the original 4 elements to only "1111" and "4444" element.
Java code
var checkboxlist = new array();checkboxlist.push("1111");checkboxlist.push("2222");checkboxlist.push("3333");checkboxlist.push("4444");// Starting from the second element of the array, remove 2 elements. checkboxlist.splice(1,2);alert(checkboxlist);

Insertion (replacement) example:
splice(addindex,replacecount,elememt...);
addindex: insert (replace) starting position, which is the array Subscript, starting from 0.
replacecount: The number of elements that need to be replaced.
elememt...: New element, which can be one or more.

When replacecount is less than or equal to 0, only add.
For example: insert two elements "aaaa" and "bbbb" after the first element ("1111") of the checkboxlist array.
Java code
var checkboxlist = new array("1111","2222","3333","4444","5555");checkboxlist.splice(1,0,"aaaa","bbbb");alert( checkboxlist);

When replacecount is greater than 0, the element will be replaced.
For example: replace the element (that is, "2222") after the first element ("1111") of the checkboxlist array with "aaaa", "bbbb". The latest value of checkboxlist in the code below is: "1111", "aaaa", "bbbb", "3333", "4444", "5555"
Java code
var checkboxlist = new array("1111", "2222", "3333","4444","5555");checkboxlist.splice(1,1,"aaaa","bbbb");alert(checkboxlist);

If the value of the replacecount parameter is greater than the length of the array, it will Replace all elements starting with the addindex parameter. After execution, the elements of the checkboxlist become: "1111", "aaaa", "bbbb"
Java code
var checkboxlist = new array("1111", "2222", "3333", "4444", "5555") ;checkboxlist.splice(1,9,"aaaa","bbbb");alert(checkboxlist);

2.5 reverse() Reverse the order of array elements
Java code
checkboxlist.reverse();

2.6 sort() Sort array elements in natural order
Java code
checkboxlist.sort();

2.7 concat() copies another array, generates a new array, and returns the elements in
alllist as a collection of elements in checkboxlist and radiolist
Java code
var checkboxlist = new array("1111","2222");var radiolist = new array("aaaa","bbbb");var alllist = checkboxlist.concat(radiolist);

2.8 slice() copy Specify the element after the serial number, generate a new array, and return
slice(index)
index: copy starting position, which is the subscript of the array, starting from 0.
When the index is greater than the number of array elements, an empty array is returned.

Copy all elements after the first element of the checkboxlist to the new temparray array, and the original checkboxlist will not change.
Java code
var checkboxlist = new array("1111","2222","3333");var temparray = checkboxlist.slice(1);

2.9 join() string operation
join(separator);
separator: The added separator can be "" empty string.

Can perform efficient string addition. Much more efficient than direct string addition.
Code example:
Java code
var checkboxlist = new array("1111","2222","3333","4444");var strdata = checkboxlist.join("|");alert(strdata);

2.10 length attribute
length returns the length of the array, which is the number of elements.
Java code
var checkboxlist = new array("1111","2222","3333","4444");alert(checkboxlist.length);