


Javascript form validation-first introduction to regular expressions_javascript skills
Recommended reading: Javascript form validation length
Javascript form validation-submit form
Javascript form validation - unveiling regular expressions
JavaScript can be used to validate these input data in HTML forms before the data is sent to the server.
Verification date
The format of the date is relatively special and cannot be verified based on its length alone
Common date format: first use two digits to represent the day, then use two digits to represent the month, and finally use four digits to represent the year, with the period separated by a slash.
MM/DD/YYYY
Blogger: How to design a code that verifies whether the date conforms to the format?
Let’s first look at the logic of validating the date format
Take out the value in the form field and use "/" to split the string into an array
Analyze the "month" substring to see if it has only two characters and both are numbers
Analyze the "day" substring to see if it has only two characters and both are numbers
Analyze the "year" substring to see if it has only four characters and are all numbers
If the above conditions are met, it is also necessary to determine whether the input data has only two slashes. If there are more than two slashes, the subsequent content should be ignored
Blogger: Don’t be afraid, Javascript is quite powerful. It provides developers with a powerful built-in tool - regular expressions
It is specifically used to match text patterns
It is like a policeman with bright eyes, always observing every move of the suspect, and once he breaks the law, he will catch the bad guy╮(╯▽╰)╭
Now let’s look at a small example
Match pattern=/^d{5}$/
The character after the equal sign is the following expression
The first slash and the last slash: "/" regular expressions are surrounded by slashes
The second character: "^" character must start with the specified pattern, numbers cannot be used
The third character: "d" represents a number
Fourth character: "{5}" The only number must be repeated 5 times
The fifth character: "$" The string ends with the specified pattern
Well, the editor will introduce you to this much about Javascript form validation - the first knowledge of regular expressions. The next section will unveil regular expressions for you. For more content, please pay attention to the Script House website!

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