Get a nested object property by passing a dot notation string as the property name

getProperty.js

/**
 * A function to take a string written in dot notation style, and use it to
 * find a nested object property inside of an object.
 *
 * Useful in a plugin or module that accepts a JSON array of objects, but
 * you want to let the user specify where to find various bits of data
 * inside of each custom object instead of forcing a standardized
 * property list.
 *
 * @param String nested A dot notation style parameter reference (ie "urls.small")
 * @param Object object (optional) The object to search
 *
 * @return the value of the property in question
 */

function getProperty( propertyName, object ) {
  var parts = propertyName.split( "." ),
    length = parts.length,
    i,
    property = object || this;

  for ( i = 0; i < length; i++ ) {
    property = property[parts[i]];
  }

  return property;
}

test.js

/*
 * Get a nested object property by passing a dot notation string as the property name
*/

// Use this
function getDescendantProp(obj, desc) {
  var arr = desc.split('.');
  while (arr.length && (obj = obj[arr.shift()]));
  return obj;
}

// Or this
function getProperty(object, propertyName) {
  var parts = propertyName.split( "." ),
      length = parts.length,
      i,
      property = object || this;
  for (i = 0; i < length; i++) {
    property = property[parts[i]];
  }
  return property;
}

// i18n with params
function text(name, params = {}) {
    var i18n = 
    {
    		"about": "About",
        "account": {
        		"welcome": "Welcome "+params.username,
            "info": "Something here."
        }
    };
    
    var obj = getDescendantProp(i18n, name);
    //var obj = getProperty(i18n, name);
    
    return obj;
}

var result = text('account.welcome', {username: 'Brynner'});

document.querySelector('#result').innerHTML = result;

https://jsfiddle.net/brynner/nyvsmh0x/