Array Methods

© Copyright 2014, Fred McClurg All Rights Reserved

2

Manipulating Arrays

Examples:

var city = [ "Santa Fe", "Cedar Rapids" ];

// overwrite first elementcity[0] = "Des Moines";

// append element to array endcity[city.length] = "Iowa City";

// display entire arrayconsole.log( city );

manipArray.html

3

Array Method: pop()

Discussion:

Array method “pop()” removes the last element from the array.

Example:

var marx = [ "Chico", "Harpo", "Groucho", "Gummo", "Zeppo" ];

console.log( "Array before pop: " + marx );

// remove last element from arrayvar youngest = marx.pop(); // "Zeppo"

console.log( "Returned from pop(): " + youngest );console.log( "Array after pop(): " + marx );arrayPop.html

4

Array Method: push()

Discussion:

The method “push()” appends an element to the end of an array.

Example:

var marx = [ "Chico", "Harpo" ];console.log( "Original array: " + marx );

// append element to array endmarx.push( "Grocho" );console.log( "After push(): " + marx );

arrayPush.html

5

Discussion:

The method “shift()” removes the first element from an array.

Example:

var bears = [ "Goldilocks", "Mama", "Papa" ];console.log( "Original array: " + bears );

// remove first element from arrayvar girl = bears.shift(); // "Goldilocks"

console.log( "Returned from shift(): " + girl );console.log( "Array after shift(): " + bears );

Array Method: shift()

arrayShift.html

6

Array Method: unshift()

Discussion:

The method “unshift()” adds an element to the beginning of the array.

Example:var bears = [ "Mama", "Papa" ];console.log( "Original array: " + bears );

// insert first element into arraybears.unshift( "Baby" );console.log( "After unshift(): " + bears );

arrayUnshift.html

7

Array Method: splice()

Discussion:

This method adds or removes elements from an array.

Example:

var taylor = [ "Andy", "Barney", "Gomer", "Aunt Bee", "Opie", ];

console.log( "Original array: " + taylor );

// starting at taylor[1] remove two elementsdeputy = taylor.splice( 1, 2 );

console.log( "Array after splice(1, 2): " + taylor );console.log( "Returned by splice(1, 2): " + deputy );

arraySplice.html

8

Array Method: slice()

Discussion:

Selects elements from an the array but does not modify the original array.

Example:

var hecks = [ "Mike", "Frankie", "Axl", "Sue", "Brick" ];

// copy "Axl" and "Sue"var oldestKids = hecks.slice(2, 4);

console.log( "hecks: " + hecks );console.log( "oldestKids: " + oldestKids );arraySort.html

9

Array Method: sort()

Discussion:

This method sorts the elements of the array.

Example:

var dwarfs = [ "Doc", "Grumpy", "Happy", "Sleepy", "Bashful", "Sneezy", "Dopey" ];

console.log( "Original array: " + dwarfs );

dwarfs.sort();console.log( "Array after sort(): " + dwarfs );

arraySort.html

14

Discussion:

Split breaks an string into array elements. Reverse changes the array order. Join combines array elements back into a string.

Example (convert string to backwards):

var word = "stressed";console.log( "Original word: " + word );

var letters = word.split( "" ); // convert string to arrayconsole.log( "Array after split(): " + letters );

letters.reverse(); // reverse array orderconsole.log( "Array after reverse(): " + letters );

var backward = letters.join( "" ); // convert array to strconsole.log( "Word after join(): " + backward );

Array Methods: split(), reverse(), join()

arraySplitRevJoin.html