gecko/js/tests/ecma_3/Object/shell.js

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/*
 * Date: 14 Mar 2001
 *
 * SUMMARY: Utility functions for testing objects -
 *
 * Suppose obj is an instance of a native type, e.g. Number.
 * Then obj.toString() invokes Number.prototype.toString().
 * We would also like to access Object.prototype.toString().
 *
 * The difference is this: suppose obj = new Number(7).
 * Invoking Number.prototype.toString() on this just returns 7.
 * Object.prototype.toString() on this returns '[object Number]'.
 *
 * The getJSType() function below will return '[object Number]' for us.
 * The getJSClass() function returns 'Number', the [[Class]] property of obj.
 * See ECMA-262 Edition 3,  13-Oct-1999,  Section 8.6.2 
 */
//-----------------------------------------------------------------------------

gTestsubsuite = 'Object';

var cnNoObject = 'Unexpected Error!!! Parameter to this function must be an object';
var cnNoClass = 'Unexpected Error!!! Cannot find Class property';
var cnObjectToString = Object.prototype.toString;
var GLOBAL = 'global';

// checks that it's safe to call findType()
function getJSType(obj)
{
  if (isObject(obj))
    return findType(obj);
  return cnNoObject;
}


// checks that it's safe to call findType()
function getJSClass(obj)
{
  if (isObject(obj))
    return findClass(findType(obj));
  return cnNoObject;
}


function findType(obj)
{
  return cnObjectToString.apply(obj);
}


// given '[object Number]',  return 'Number'
function findClass(sType)
{
  var re =  /^\[.*\s+(\w+)\s*\]$/;
  var a = sType.match(re);
 
  if (a && a[1])
    return a[1];
  return cnNoClass;
}


function isObject(obj)
{
  return obj instanceof Object;
}