title: handle mutiple duplicate error mongoose nodejs
body: <p>I have User Schema like this</p>
  
  <pre><code>const UserSchema = new Schema({
    username: {
      type: String,
      unique: true,
      required: true,
      lowercase: true,
      trim: true
    },
    email: {
      type: String,
      unique: true,
      required: true
    },
  
    phoneNumber: {
      type: Number,
      unique: true,
      required: true
    },
  });
  </code></pre>
  
  <p>When I post a user with duplicate <code>name</code>, <code>phonenumber</code> or <code>email</code>. I receive the error like this:
  This is error message <code>E11000 duplicate key error collection: project.users index: username_1 dup key: { : "john" }</code></p>
  
  <p>So my question is that how I can know it is a duplicate name or duplicate phonenumber. I want to receive the error like this.</p>
  
  <pre><code>This phone number has been already used
  This name has been already used
  </code></pre>