React - uncaught TypeError: Cannot read property 'setState' of undefined

Question

I am getting the following error

Uncaught TypeError: Cannot read property \'setState\' of undefined

even after binding delta in

Answer 1

1. Check state check state whether you create particular property or not

this.state = {
            name: "",
            email: ""
            }
            
           
            
this.setState(() => ({ 
             comments: comments          //comments not available in state
             })) 

2.Check the (this) if you doing setState inside any function (i.e handleChange) check whether the function bind to this or the function should be arrow function .

## 3 ways for binding this to the below function##

//3 ways for binding this to the below function

handleNameChange(e) {  
     this.setState(() => ({ name }))
    }
    
// 1.Bind while callling function
      onChange={this.handleNameChange.bind(this)}
      
      
//2.make it as arrow function
     handleNameChange((e)=> {  
     this.setState(() => ({ name }))
     })
    
//3.Bind in constuctor 

constructor(props) {
        super(props)
        this.state = {
            name: "",
            email: ""
        }
        this.handleNameChange = this.handleNameChange.bind(this)
        }