反应-检查对象是否处于状态变量

Question

I have a state variable that is a object (called testObject). I store several objects in that state variable. Iam looking for a way to check if a object already exists in that state variable then remove it if true.

so to sum up the dilemma:

• check if a object is already in testObject
• If true => delete that object

• if false => add the object to testObject

  class Connector extends Component {

   constructor(props) { super(props); this.state=({ testObject: {}, }); console.log(this.props); } 

  }

Answer 1

How about toggling the state?

this.setState(prevState => ({
  testObject: {
    ...prevState.testObject,
    someProperty: !prevState.testObject.someProperty
  }
}))

Answer 2

You can check it by this way:

if (this.state.testObject.hasOwnProperty(property_name))
  delete this.state.testObject.property_name
else {
  var testObject = this.state.testObject
  testObject[property_name] = some_value
  this.setState({testObject: testObject})
}

Answer 3

This code will delete the testObject key from the state if present.

Assuming that obj is the object you want to delete/add.

let newState = this.state.testObject

if (this.state.testObject.obj) {
    delete newState["obj"]
} else {
    newObject["obj"] = "value"
}

this.setState({ testObject: newState })

if the obj is present in testObject, then it will delete it, else it will insert obj in testObject.

Answer 4

lets say the object in question is in testObject with key obj and the incoming var is newTestObj.

then we will check

if(this.state.testObject && this.state.testObject.obj) {
   let tempObj = this.state.testObject;
   delete tempObj.obj;
   this.setState({
      testObject: tempObj
   })
}else {
  this.setState({
      testObject: {...testObject, obj: newTestObj.obj}
   })
}

Answer 5

use an if statement to check if the object exists.

if(this.state.objectName)
  delete this.state.objectName