See Also

Description

Generates an error condition that can be handled by a try...catch statement.

Syntax

throw exception

The exception argument can be any expression.

Remarks

The following example throws an error based on a passed-in value, then illustrates how that error is handled in a hierarchy of try...catch statements:

function TryCatchDemo(x)
{
  try {
    try {
    if (x == 0)					// Evalute argument.
      throw "x equals zero";			// Throw an error.
    else
      throw "x does not equal zero";		// Throw a different error.
    }
    catch(e) {					// Handle "x = 0" errors here.
      if (e == "x equals zero")			// Check for an error handled here.
        return(e + " handled locally.");	// Return object error message.
      else					// Can't handle error here.
        throw e;					// Rethrow the error for next
    }							// error handler.
  }
  catch(e) {                    	   	// Handle other errors here.
    return(e + " handled higher up.");		// Return error message.
  }
}
document.write(TryCatchDemo(0));
document.write(TryCatchDemo(1));