Helper functions in JavaScript

hasNestedProperties.js

/**
 * hasNestedProperties check if an object has the nested
 * properties passed in params
 * 
 * @param  {Object}  obj         object we want to test
 * @param  {String}  properties  nested property we want
 * @return {Boolean}             either the object has these
 *                               nested properties or not
 */
 
  function hasNestedProperties(obj, properties) {
    var properties = properties.split('.');
    var property;
 
    // For each properties, check if it's an object property
    for(var i = 0, l = properties.length; i < l; i++) {
      property = properties[i];
      if(!obj.hasOwnProperty(property)) {
        return false;
      }
      obj = obj[property];
    }
    
    return true;
  }
  
/**
 * Use cases:
 
   var jSnow = { 
     name: {
       firstname:  'Jon',
       lastname: 'Snow' 
     }
   };
   var firstName  = hasNestedProperties(jSnow, 'name.firstname');  // = true
   var familyName = hasNestedProperties(jSnow, 'name.familyName'); // = false
   var deepNested = hasNestedProperties(jSnow, 'someRandom.property.unexistent'); // = false
 
 * It avoids syntax like:
 
    if(jSnow.name && jSnow.name.firstname && jSnow.name.firstname.whatever && ...) {
      console.log(jSnow.name.firstname.whatever);
    }
    
 */

function hasNestedProperties(obj, properties) {
    // For each properties, check if it's an object property
    properties.split('.').forEach(function(property) {
        if (!obj.hasOwnProperty(property)) {
            return false;
        }
        obj = obj[property];
    }

    return true;
}