number Property (Error)

number Property (Error) (JavaScript)


Returns or sets the numeric value associated with a specific error. The Error object's default property is number.

.number [= errorNumber]


Any instance of the Error object.


An integer representing an error.

An error number is a 32-bit value. The upper 16-bit word is the facility code, and the lower word is the error code. To determine the error code, use the & (bitwise And) operator to combine the number property with the hexadecimal number 0xFFFF.


The following example causes an exception to be thrown and displays the error code that is derived from the error number.

    // Cause an error.
    var x = y;
    document.write ("Error Code: ");
    document.write (e.number & 0xFFFF)
    document.write ("<br />");

    document.write ("Facility Code: ")
    document.write(e.number>>16 & 0x1FFF)
    document.write ("<br />");

    document.write ("Error Message: ")
    document.write (e.message)


The output of this code is as follows.

Error Code: 5009
Facility Code: 10
Error Message: 'y' is undefined


Supported in the following document modes: Quirks, Internet Explorer 6 standards, Internet Explorer 7 standards, Internet Explorer 8 standards, Internet Explorer 9 standards, Internet Explorer 10 standards, Internet Explorer 11 standards. Also supported in Store apps (Windows 8 and Windows Phone 8.1). See Version Information.

Applies To: Error Object (JavaScript)

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