Method Function.setErrorHandler

Set a error handler for the function.

• Syntax Function Function.setErrorHandler(Function f , [ Number v ])
  
  When called this method will wrap the caller function in a try/catch block and return this as a new function. If an error is subsequently thrown by the function, execution will be passed to the error handler f which is provided as the first argument.
  
  The error handler itself is passed two parameters - the function which caused the error and the error object which was thrown.
  
  If an error occurs the return value from the error handler is passed as the return value of the calling function.
• Parameters

  Function f

  The handler which should execute if the function throws an error.

  Number v (Optional)

  This parameter sets the verbosity level when the error handler is used with the JSLab error object.

• Return value A new function wrapped in a try/catch block
• Examples

  Setting an error handler for a given function.

  // Create function with intentional error
  function myFunc(s) {
    alert(s);
    notDeclared
  }
  
  // Create error handler function with 2 parameters f and e
  // f is the function throwing the error
  // e is the error object
  function eHandler(f,e) {
    // Error handling code goes here
    alert('Now fixing error');  
  }
  
  // Now we assign the error handler
  myFunc = myFunc.setErrorHandler(eHandler);
  // Try to execute myFunc
  myFunc('Hello world');
  // Output is 'Hello World' followed by 'Now fixing error'

• Related Function.removeErrorHandler   
• Resources You can use this function along with the JSLab Error object and the JSLab XHR object for an easy way to report client side errors to a server for logging. See the article Auto reporting JavaScript errors for more information.
• Download
  Download this function including dependencies
  Source

  Unless otherwise noted all code in the JSLab Standard Library is licensed as GPLv3. See http://www.gnu.org/licenses/gpl.html for the entire license.

  // ************************************************************************** // Copyright 2007 - 2009 Tavs Dokkedahl // Contact: http://www.jslab.dk/contact.php // // This file is part of the JSLab Standard Library (JSL) Program. // // JSL is free software; you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by // the Free Software Foundation; either version 3 of the License, or // any later version. // // JSL is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // // You should have received a copy of the GNU General Public License // along with this program. If not, see <http://www.gnu.org/licenses/>. // *************************************************************************** // Set an error handler for a function Function.prototype.setErrorHandler = function(f,v) { // Throw error if no user function is provided if (!f) throw new Error('Function.setErrorHandler: No function provided.'); var that = this; // New function to return var g = function() { try { var a = []; for(var i=0; i<arguments.length; i++) a.push(arguments[i]); that.apply(null,a); } catch(e) { return f(g,e,v); } }; // Save ref. to original function g.old = this; return g; };