Node.js lodash implicit chaining

var _ = require('lodash');

var people = [//from  w w  w. j a  va  2  s . c o m
  { id: 1, name: "Jim", age: 20, gender: 'm', enabled: true },
  { id: 1, name: "Jim", age: 20, gender: 'm', enabled: false },  
  { id: 2, name: "Bob", age: 34, gender: 'm', enabled: true },
  { id: 3, name: "Steve", age: 30, gender: 'm', enabled: true },
  { id: 4, name: "Nancy", age: 42, gender: 'f', enabled: true },
  { id: 5, name: "Frank", age: 30, gender: 'm', enabled: true },
  { id: 6, name: "Larry", age: 68, gender: 'm', enabled: true }
];

// Implicit Chaining : 
// Chainable functions return wrapped values, 
// must call 'value()' to get the result

var r = _(people)
      .filter({enabled: true})
      .filter({gender: 'm'})
      .map('id')
      .value();

console.log(r);  


// Implicit Chaining : Non-chainable functions return primitive values    

r = _(people)
      .filter({enabled: true})
      .filter({gender: 'm'})
      .first();

console.log(r);    

// Chaining can wrap plain objects and strings 

var i = _(r)
      .extend({something: true})
      .extend({another: 12})
      .value();


console.log(i);