jQuery更多变量分号或逗号-基本

Question

I know we can just use one var for many variables and use comma to separate them

var text1 = 'abc',
    text2 = 'bcd',
    text3 = 'dfg'

but if my variables are

var text1 = 'abc',
    text2 = 'bcd',
    text3 = 'dfg',
    text4 = $(this).find('div').next('li');
    text5 = $(this).find('div2').next('li2');

I found comma at the end of text4 is not correct, if the case like that do we still need comma to separate or semicolon with a var in the front?

Answer 1

var var1 = val1,
    var2 = val2;

is equivalent to:

var var1 = val1;
var var2 = val2;

Commas are for separating multiple variable declarations within one var statement, semicolons are for separating multiple statements. So when you use semicolon, you have to use the var keyword again because you're starting a new statement.

If you use a semicolon and don't use the var keyword in the new statement, you'll be assigning a global variable, not declaring a local one.

Answer 2

Here's a visual answer; JavaScript interprets your code like this:

var text1 = 'abc',
    text2 = 'bcd',
    text3 = 'dfg',
    text4 = $(this).find('div').next('li');

text5 = $(this).find('div2').next('li2');

This is a great example of a semantic error, meaning that your code is syntactically correct but does not do what you meant. Importantly, JavaScript will make text5 a global variable because it was declared without var .

See these two SO questions for more information:

1. What is the purpose of the var keyword and when to use it (or omit it)?
2. Declaring Multiple Variables in JavaScript