How to automatically assign value to another key depending on some other key's value in an Object

Question

How do you achieve the following thing in Javascript

1) var MyObject={
2)    tableView:true,
3)    chartView:!(this.tableView)
4) }

The code at line number 3 is not working. Whats wrong in that line?

What i basically want to do is set "chartView" to opposite of "tableView" whenever tableView is set from code.

Answer 1

Since you're in the process of creating the object, this is not bound to that object. Moreover, since you want chartView to always evaluate to the opposite of tableView , even if the latter changes further down the line, a function would be a better approach:

var MyObject = {
    tableView: true,
    chartView: function() {
        return !this.tableView;
    }
};

Now you can do:

var chartView = MyObject.chartView();  // false.
MyObject.tableView = false;
chartView = MyObject.chartView();      // true.

Answer 2

You can't use this to refer to an object in an object literal's properties. You can use this inside a function that is a method of that object:

var MyObject = {
  tableView: true,
  chartView: function () {
    return !this.tableView;
  }
}

Answer 3

Based on your requirement, this may be an answer too,

 var MyObject = {
      view : function(bool){
         this.tableView = bool;
         this.chartView = !(bool); 
      }
      tableView: true,
      chartView: false
    } 

    MyObject.view(false)

    console.log(MyObject.tableView);     // Outputs false
    console.log(MyObject.chartView)      // Outputs true

This way you will always have opposite of tableView in chartView with a single function call.