JavaScript syntax
avaScript is a programming language. Grammar rules define the structure of a language.
JavaScript Syntax
JavaScript is a scripting language.
It is a lightweight, yet powerful programming language.
JavaScript Literal
In a programming language, a literal is a constant, as in 3.14.
Number literal can be an integer or a decimal, or scientific notation (e).
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
</head>
<body>
<p id="demo"></p>
<script>
document.getElementById("demo").innerHTML = 123e5;
</script>
</body>
</html>Run the program and try it
String literal You can use single quotes or double quotes:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
</head>
<body>
<p id="demo">andy</p>
<script>
document.getElementById("demo").innerHTML = 'liu qi';
</script>
</body>
</html>Run the program and try it
Expression literals are used for calculations:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
</head>
<body>
<p id="demo"></p>
<script>
document.getElementById("demo").innerHTML = 5 * 10;
</script>
</body>
</html>Run the program and try it
Array (Array) literals define an array:
[40, 100, 1, 5, 25, 10]
Object literal defines an object:
{firstName: "John", lastName:"Doe", age:50, eyeColor:"blue"}
Function (Function) literal defines a function:
function myFunction(a, b ) { return a * b;}
#JavaScript Variable
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
</head>
<body>
<p id="demo"></p>
<script>
var length;
length = 6;
document.getElementById("demo").innerHTML = length;
</script>
</body>
</html>Run the program and try itJavaScript Operator
JavaScript uses arithmetic operators to calculate values:<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
</head>
<body>
<p id="demo"></p>
<script>
document.getElementById("demo").innerHTML = (5 + 6) * 10;
</script>
</body>
</html>Run the program to try itJavaScript uses assignment operators to variables Assignment:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
</head>
<body>
<p id="demo"></p>
<script>
var x, y, z;
x = 5
y = 6;
z = (x + y) * 10;
document.getElementById("demo").innerHTML = z;
</script>
</body>
</html>Run the program and try itThe JavaScript language has many types of operators:
| Instance | Description | ||
|---|---|---|---|
| = + - * / | Description in JS operators | ||
| == != < > | Comparison in JS Operators are described in |
| abstract | else | instanceof | super |
| boolean | enum | int | switch |
| break | export | interface | synchronized |
| byte | extends | let | this |
| case | false | long | throw |
| catch | final | native | throws |
| char | finally | new | transient |
| class | float | null | true |
| const | for | package | try |
| continue | function | private | typeof |
| debugger | goto | protected | var |
| default | if | public | void |
| delete | implements | return | volatile |
| do | import | short | while |
| double | in | static | with |
JavaScript 对大小写敏感。
JavaScript 对大小写是敏感的。
当编写 JavaScript 语句时，请留意是否关闭大小写切换键。
函数 getElementById 与 getElementbyID 是不同的。
同样，变量 myVariable 与 MyVariable 也是不同的。
- Course Recommendations
- Courseware download
The courseware is not available for download at the moment. The staff is currently organizing it. Please pay more attention to this course in the future~ 