JavaScript isset() equivalent PHP isset()

PHP isset() equiv JavaScript isset() funciton:

Often I am get asked from junior developers that, Is there any isset() function in Javascript? Ha ha ha. I ignore them, but let them try to create a custom function to do this job.
Ok no more words...Let get it...

/**
 * 
 * @returns {Boolean}
 * Original by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
 * Improved by: FremyCompany
 * Improved by: Onno Marsman
 * Improved by: Rafał Kukawski
 * Example-1: isset( undefined, true);
 * Returns: false
 * Example 2: isset( 'Kevin van Zonneveld' );
 * Returns: true
 */
function isset ()
{

  var a = arguments,
    l = a.length,
    i = 0,
    undef;

  if (l === 0)
  {
    throw new Error('Empty isset');
  }

  while (i !== l)
  {
    if (a[i] === undef || a[i] === null)
    {
      return false;
    }
    i++;
  }
  return true;
}

But........
The problem is this will raise an exception when calling isset(abc.def.ghi) in case if abc.defis undefined. However by combining this solution with the one that accepts a variable name in a form of a string, it will be identical to the PHP version

You can use this function as PHP isset() given to use.

var a;

a = {
    b: {
        c: 'e'
    }
};

function isset (obj, path) {
    var stone;

    path = path || '';

    if (path.indexOf('[') !== -1) {
        throw new Error('Unsupported object path notation.');
    }

    
    path = path.split('.');
    
    do {
        if (obj === undefined) {
            return false;
        }

        stone = path.shift();
        
        if (!obj.hasOwnProperty(stone)) {
            return false;
        }
        
        obj = obj[stone];
        
    } while (path.length);

    return true;
}

console.log(
    isset(a, 'b') == true,
    isset(a, 'b.c') == true,
    isset(a, 'b.c.d') == false,
    isset(a, 'b.c.d.e') == false,
    isset(a, 'b.c.d.e.f') == false
);

Another Way to do isset() function using javascript.

if(typeof(data.length) != 'undefined')
    {
       // do something
    }

    if(empty(data))
    {
        // do something
    }

   if(typeof(data) == 'undefined' || data === null)
   {
     //do something
   }

Tags: advanced php → best coding → javascript → php javascript

JavaScript isset() equivalent PHP isset()

By Game Changer → Thursday, December 17, 2015