Uncaught TypeError: Cannot set property ‘todoText’ of undefined

Working on the Javascript objects and functions. Facing issue with it.

  var todoList = {
      todo:[],
      displayTodo:function(){
        console.log('My Todo:',this.todo); 
      },
      addTodo:function(todoText){
        this.todo.push({
          todoText:todoText,
          complete:false
        });
        this.displayTodo();
      },
      changeTodo:function(posi,newTodo){
        //this.todo[posi] = newTodo; 
        this.todo[posi].todoText=newTodo;
        this.displayTodo();
      },
      toggleComplte:function(posi){
        var todo = this.todo[posi];
        todo.complete = !todo.complete;
        this.displayTodo();
      }
    }


    todoList.toggleComplte(0)

Error I got when running.

VM1196:16 Uncaught TypeError: Cannot set property 'todoText' of undefined
    at Object.changeTodo (<anonymous>:16:29)
    at <anonymous>:21:10

Can some one suggest what is the error ?


Source: stackoverflow-javascript