How to use JavaScript Throw statement

This article mainly introduces "how to use JavaScript Throw sentences". In daily operation, I believe many people have doubts about how to use JavaScript Throw sentences. The editor consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful to answer the doubts about "how to use JavaScript Throw sentences". Next, please follow the editor to study!

Throw statement

The throw statement allows us to create custom errors.

The correct technical term is to create or throw an exception.

If you use throw with try and catch, you can control the program flow and generate custom error messages.

Grammar

Throwexception

Exceptions can be JavaScript strings, numbers, logical values, or objects.

Example

This example detects the value of the input variable. If the value is wrong, an exception (error) is thrown. Catch catches the error and displays a custom error message:

Example

Function myFunction () {

Var message, x

Message = document.getElementById ("message")

Message [XSS _ clean] = ""

X = document.getElementById ("demo") .value

Try {

If (x = "") throw "value is empty"

If (isNaN (x)) throw "not a number"

X = Number (x)

If (x

< 5) throw "太小"; if(x >

10) throw is "too big"

}

Catch (err) {

Message [XSS _ clean] = "error:" + err

}

}

Note that if the getElementById function goes wrong, the above example will also throw an error.

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