Js array and splice usage how to use js array and splice

First, add a splice function:

Splice: This method is used to delete an element from the array.

Array. splice (index, count, value ....);

Index: indicates which subscript starts,

Count: number of elements deleted

Value: indicates the added element.

Example:

1. var array = new Array (1, 2, 3, 4, 5, 6 );

Array. splice (0, 1, 2)

Result: 2, 2, 3, 4, 5

2. var array = new Array (1, 2, 3, 4, 5, 6 );

Array. splice (0, 0, 2)
Result: 2, 1, 2, 3, 4, 5

3. var array = new Array (1, 2, 3, 4, 5, 6 );

Array. splice (0, 0, 2, 3, 4)

2, 3, 4, 1, 2, 3, 4, 5, 6

1. Create an array

Var arr = new Array (); arr [0] = "aaa"; arr [1] = "bbb"; arr [2] = "ccc ";

Var a = [1, 2, 3, 4, 5];

Var c = new Array ("first", "second", "third ");

Or the number of arrays directly:

Var d = ["first", "second", "third"];

Var arrayObj = new Array (); // create an Array var arrayObj = new Array ([size]); // create an Array and specify the length. Note that it is not the upper limit, is the length var arrayObj = new Array ([element0 [, element1 [,... [, elementN]); // creates an array and assigns a value.

It should be noted that, although the second method creates an array with a specified length, the array actually gets longer in all cases, that is, even if the length is 5, you can still store elements outside the specified length. Note: the length will change accordingly.

2. Access to array elements

Var testGetArrValue = arrayObj [1]; // Obtain the array element value arrayObj [1] = "this is a new value"; // assign a new value to the array element

3. Add array elements

ArrayObj. push ([item1 [item2 [... [itemN]); // add one or more new elements to the end of the array, and return the new length of the array arrayObj. unshift ([item1 [item2 [.. [itemN]); // adds one or more new elements to the array. The elements in the array are automatically removed and the new length of arrayObj is returned. splice (insertPos, 0, [item1 [, item2 [,... [, itemN]); // insert one or more new elements to the specified position of the array. The inserted element is automatically removed and "" is returned "".

4. Deletion of array elements

Var a = new Array ("first", "second", "third"); delete a [1]; document. write (a. length)

// The result is 3, indicating that the length of the array cannot be changed even if it is deleted.

ArrayObj. pop (); // remove the last element and return the value of arrayObj. shift (); // remove the first element and return the element value. The elements in the array are automatically moved forward to arrayObj. splice (deletePos, deleteCount); // deletes the specified number of deleteCount elements starting from deletePos in the specified position. The removed elements are returned in an array.

5. Truncate and merge arrays

ArrayObj. slice (start, [end]); // return part of the array in the form of an array. Note that the elements corresponding to the end are not included. If the end is omitted, all the elements after the start are copied to arrayObj. concat ([item1 [, item2 [,... [, itemN]); // concatenates multiple arrays (or strings, or arrays and strings) into an array and returns a new connected array.

6. Copy an array

ArrayObj. slice (0); // returns the Copy array of the array. Note that it is a new array instead of pointing to arrayObj. concat (); // returns the Copy array of the array. Note that it is a new array, not pointing

7. Sorting of array elements

ArrayObj. reverse (); // returns the array address arrayObj. sort (); // sorts array elements and returns the array address.

8. Stringized array elements

ArrayObj. join (separator); // returns a string that connects each element value of the array and is separated by separator. ToLocaleString, toString, valueOf: can be considered as a special use of join, not commonly used

The above is all about the use of js arrays and splice. I hope you will gain some benefits after reading this article.