Common JavaScript verification function examples _ javascript skills

This article mainly introduces common JavaScript verification functions. Examples summarize many common js verification functions and related skills, such as string verification, form verification, and common js special effects, which are of great practical value, you can refer to the examples in this article to summarize common JavaScript verification functions. Share it with you for your reference. The specific summary is as follows:

1. String Verification

1. length limit

The Code is as follows:

Script
Function test ()
{
If (document. a. B. value. length> 50)
{
Alert ("cannot exceed 50 characters! ");
Document. a. B. focus ();
Return false;
}
}
Script

2. Only Chinese characters are allowed

The Code is as follows:

3. "English only

The Code is as follows: