1, JavaScript events
Events can be used to handle form validation, user input, user behavior and browser actions:
页面加载时触发事件
页面关闭时触发事件
用户点击按钮执行动作
验证用户输入内容的合法性
等等 ...
JavaScript event code can be executed using a variety of methods:
HTML 事件属性可以直接执行 JavaScript 代码
HTML 事件属性可以调用 JavaScript 函数
你可以为 HTML 元素指定自己的事件处理程序
你可以阻止事件的发生。
等等 ...
2, JavaScript string
The string can store a series of characters, such as "John Doe".
String can be inserted into any character in quotation marks. You can use single or double quotes:
Example
var carname = "Volvo the XC60";
var = carname 'Volvo the XC60';
2.1, you can use the index to access the location of each character in the string:
Examples
var character = carname [7];
The index of the string starting from 0, which means that the first character index value of [0], the second is [1], and so on.
2.2, string length
The length of the string can be calculated using the built-in property length:
Example
var TXT = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
var txt.length = SLN;
3, JavaScript operator
Operator = to assign.
Value for the + operator.
Operator = to a JavaScript variable.
Arithmetic operator + is used to add value.
3.1, for the string operator +
...... + operator used to add text or string variable (connected).
= the txt1 "A Very What";
txt2 = "Nice Day";
txt3 = + txt2 the txt1;
txt3 calculation results are as follows:
What verynice Day A
3.2, strings of numbers and adding
Two numbers together, and returns the digital addition, if the digital sum string, the string returns,
X + =. 5. 5;
Y = ". 5" +5;
Z = "the Hello" +5;
x, y, and z as output:
10
55
Hello5
4, JavaScript comparison and logical operators
For comparison and logical operators test true or false.
4.1, comparison operators
Comparison operator in a logical statement to determine the variable or values are equal.
4.2, logical operators
Logical operators for determining the logical connection between the variable or value.
Given x = 6 and y = 3, the following table explains the logical operators:
4.3, conditional operator
