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<香港科技大学html+css+js课堂笔记>week2--javaScript部分

2016-03-21 18:15 411 查看
1.格式：

<!DOCTYPE html>

<html>

<head>

. . . load JavaScript libraries here . . .

</head>

<body>

. . . your JavaScript code typically goes at the end of body . . .

</body>

</html>

2.html中两种引用js方式：

1>

<script>

function surprise() {

alert("Hello!");

}

</script>

2>

<script src="mycode.js"></script>

In mycode.js:

function surprise() {

alert("Hello!");

}

3.

There are 3 JavaScript popups:

1>alert();

2>confirm();

3>prompt().

1>alert("Welcome!");



2>confirm("want to go to Disneyland?");

源码：

<!doctype html>

<html>

<head>

<title>Example of confirm()</title>

<script>

if (confirm("Want to go to Disneyland?"))

document.location.href

="http://park.hongkongdisneyland.com";

</script>

</head>

</html>



3>prompt("what is your name?");

源码：

<!doctype html>

<html>

<head>

<title>Example of prompt()</title>

<script>

var user_name;

user_name=prompt("What is your name?");

document.write("Welcome to my page "

+ user_name + "!" );

</script>

</head>

</html>



4.Variables:

1>data types:

number, String, Boolean, Other(Object)

2>number:

只有一种数字类型。

var big_number = 123e5; //12300000

var small_number = 123e­5; //0.00123

3>String:

var name = "David"; 双引号

var title = 'Professor'; 单引号

var message = "It's alright"; 双引号中可以直接使用单引号。

4>Boolean:

var condition1 = true;

var condition2 = false;

5>TYPEOF:

You can use the typeof operator to check the type of a variable.

eg: typeof "bob" = String;

6>类型转换：



5.Function:

1>结构：

A function is a group of code:

function do_something() {

. . . code goes here . . .

}

Run the function like this:

do_something();

Eg:

<html>

<head>

<title>Example of a function</title>

<script>

function greet_the_user(){

alert('Hello!');

alert('We start soon...');

prompt('Excited?!')

}

</script>

</head>

<body onload="greet_the_user()">

</body>

</html>

2>recursive:

Eg:

<!doctype html>

<html><body>

<script>

alert("It's my " + build_great(5) +

"grandmother!");

function build_great( depth ) {

if (depth > 0)

return "great " + build_great( depth ­ 1 );

else

return "";

}

</script>

</body></html>

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