title: compare first property of two object and merge
body: <p>i have one question for compate two object property i have two object with different value i want to compare object and if first property in both object then change property value 
  this is my object </p>
  
  <p>1)</p>
  
  <pre><code>obj1 = {A: 1001, B: 3147020, C: 30},
  {A: 1002, B: 3147021, C: 30},
  {A: 1003, B: 3147022, C: 30};
  </code></pre>
  
  <p>2)</p>
  
  <pre><code>obj2 = {A: 1001, B: 3147020, C: 30},
  {A: 1002, B: 3147021, C: 30},
  {A: 1004, B: 3147022, C: 30};
  </code></pre>
  
  <p>when i compare if i find same value A in both object so change obj1 B value to obj2 B value 
  and if you have any ides for check in both object like obj1 all A value not same to obj2 all Value so please help me for this question  </p>