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