JavaScript (1) Array

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JavaScript

1) Create an array

var mycars = new Array();
mycars[0] = "Saab";
mycars[1] = "Volvo";
mycars[2] = "BMW";

var i;
for (i = 0; i < mycars.length; i++) {
	document.write(mycars[i] + "<br />");
}

2) Join two arrays

var parents = ["Jani", "Tove"];
var children = ["Cecilie", "Lone"];
var family = parents.concat(children);
document.write(family);

3) Join three arrays

var parents = ["Jani", "Tove"];
var brothers = ["Stale", "Kai Jim", "Borge"];
var children = ["Cecilie", "Lone"];
var family = parents.concat(brothers, children);
document.write(family);

4) Join all elements of an array into a string

var fruits = ["Banana", "Orange", "Apple", "Mango"];
document.write(fruits.join() + "<br />");
document.write(fruits.join("+") + "<br />");
document.write(fruits.join(" and "));

5) Remove the last element of an array

var fruits = ["Banana", "Orange", "Apple", "Mango"];
document.write(fruits.pop() + "<br />");
document.write(fruits + "<br />");
document.write(fruits.pop() + "<br />");
document.write(fruits);

6) Add new elements to the end of an array

var fruits = ["Banana", "Orange", "Apple", "Mango"];
document.write(fruits.push("Kiwi") + "<br />");
document.write(fruits.push("Lemon","Pineapple") + "<br />");
document.write(fruits);

7) Reverse the order of elements in an array

var fruits = ["Banana", "Orange", "Apple", "Mango"];
document.write(fruits.reverse());

8) Remove the first element of an array

var fruits = ["Banana", "Orange", "Apple", "Mango"];
document.write(fruits.shift() + "<br />");
document.write(fruits + "<br />");
document.write(fruits.shift() + "<br />");
document.write(fruits);

9) Select elements from an array

var fruits = ["Banana", "Orange", "Apple", "Mango"];
document.write(fruits.slice(0,1) + "<br />");
document.write(fruits.slice(1) + "<br />");
document.write(fruits.slice(-2) + "<br />");
document.write(fruits);

10) Sort an array (alphabetically and ascending)

var fruits = ["Banana", "Orange", "Apple", "Mango"];
document.write(fruits.sort());

11) Sort numbers (numerically and ascending)

function sortNumber(a, b) {
	return a - b;
}
var n = ["10", "5", "40", "25", "100", "1"];
document.write(n.sort(sortNumber));

12)Sort number (numerically and descending)

function sortNumber(a, b) {
	return b - a;
}
var n = ["10", "5", "40", "25", "100", "1"];
document.write(n.sort(sortNumber));

13) Add an element to an array

var fruits = ["Banana", "Orange", "Apple", "Mango"];
document.write("Removed: " + fruits.splice(2,0,"Lemon") + "<br />");
document.write(fruits);

14) Convert an array to a string

var fruits = ["Banana", "Orange", "Apple", "Mango"];
document.write(fruits.toString());

15) Add new elements to the begining of an array

var fruits = ["Banana", "Orange", "Apple", "Mango"];
document.write(fruits.unshift("Kiwi") + "<br />");
document.write(fruits.unshift("Lemon","Pineapple") + "<br />");
document.write(fruits);

数组当作一个队列或堆栈的用法

var queue = [];
queue.push(1, 2);
alert(queue.shift());

var stack = [];
stack.push(1,2);
alert(stack.pop());

数组当作一个微型数据库的用法

var database = [1, 2, 3];
database.splice(1, 0, 4); //在index=1“增加”一个元素
alert(database); 
database.splice(1, 1); // “删除”index=1的元素
alert(database);
database.splice(1, 1, 5); // “更新”index=1的元素
alert(database);
alert(database.slice(1, 2)); //“查询”index=[1, 2)的元素

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