JavaScript basic teaching thread array Array_ basics

String, numeric, and Boolean values are discrete values (scalar), and if a variable is discrete, then it has only one value at any time.

If you want to use variables to store a set of values, you need to use arrays (array).

An array is a collection of tree values with the same name, each of which is an element of an array, and can be used by the variable team to store the names of each member of the group.

In JavaScript, an array is created using a keyword array declaration, and a coworker can declare the length of the variable. For example

Copy Code code as follows:

var ateam = new Array (12);//Declare the length of a variable

When you cannot predict the final number of arrays, you can declare an array without specifying a specific number. For example:

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var ateam = new Array ();/////The final number of the array is unknown, you can not declare a specific number
Ateam[0] = 1414;
ATEAM[1] = "Beijing";
ATEAM[2] = 0x4;
ATEAM[3] = "I can";
ATEAM[4] = "red";
ATEAM[5] = "Blue";
ATEAM[6] = "orange";

Alternatively, you can create an array directly

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var ateam = new Array ("n", "Blue", "Red", "Beijing");

As with strings, arrays can also use length to get and specify the length of an array.

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var ateam = new Array ("n", "Blue", "Red", "Beijing");
document.write (ateam[1]+ "<br>");
document.write (ateam.length + "<br>")

Note: A more profound understanding of arrays.

Copy Code code as follows:

var ateam = new Array ("n", "Blue", "Red", "Beijing");
ATEAM[20] = "12415"
document.write (ateam[20]+ "<br>");
document.write (ateam.length + "<br>")

Alternatively, the array can be defined with []. Use commas to separate the middle.

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STeam = [10, "5565", "Beijing", 33263, "Red"]
document.write (steam[3])//Output 33263

Arrays can be easily converted using ToString ()

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STeam = [Ten, "5565", "pking", 33263, "Red"]
document.write (steam.tostring ())//
Output Results 10,5565,pking,33263,red
document.write (typeof (SS));
Output result string

Use the Join () method if the array is converted to a string and you do not want to use a comma connection.

Copy Code code as follows:

STeam = [Ten, "5565", "pking", 33263, "Red"]
SS = Steam.join ("-");
DD =steam.join ("[")
Output Results 10,5565,pking,33263,red
document.write (ss);
document.write (DD);
Output 10-5565-pking-33263-red 10][5565][pking][33263][red

For strings,JavaScript uses split () to convert to an array

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var fruit = "Apple,2151,orange";
Sfruit = Fruit.split (",")
document.write (Sfruit); Output Apple,2151,orange
document.write (Sfruit.join ("-")); Output Apple-2151-orange

In the example,JavaScript provides a reverse () method to invert the array.

Copy Code code as follows:

var fruit = "Apple,2151,orange";
Sfruit = Fruit.split (",")
document.write (Sfruit); Output Apple,2151,orange
document.write (Sfruit.join ("-") + "<br>"); Output Apple-2151-orange
document.write (Sfruit.reverse () + "<br>"); output orange,2151,apple
document.write (Sfruit.reverse (). toString () + "<br>"); output Apple,2151,orange

For string inversion, JavaScript has no direct conversion method, we can use split () to convert the string to an array, using Rerverse () to reverse, and then use join to connect, to achieve string inversion.

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var fruit = "2151,orange,apple";
var sfruit = "iambeijing123";
document.write (Fruit.split (","). Reverse () + "<br>");//2151,orange,apple
document.write (Sfruit.split (""). Reverse (). Join ("") + "<br>");//Output iambeijing123

Sort () enables array elements to be sorted in alphabetical order.

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Fruit = ["Orange2", "2151", "Orange", "Apple"]
document.write (Fruit.sort ());//Output Results 2151,apple,orange,orange2

About the use of push () and pop ()

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Sfruit = new Array ();
Sfruit.push ("Red");
Sfruit.push ("green");
Sfruit.push ("Oragen");
Sfruit.push ("Blue");
document.write (Sfruit.length + sfruit.tostring () + "<br>");
var wfruit = Sfruit.pop ();
document.write (wfruit+ "<br>")
document.write (sfruit.tostring ())

As above, JavaScript treats an array as a stack, using push () and pop () for stack and stack processing.