I'm trying to use getters and setters to adjust data initially set with a class constructor. The getter seems to work:

class myClass {
  constructor(sth) {
    this.data = {
      sth,
      timestamp: new Date()
    }
  }
  
  create(createData) {
    const newData = Object.assign({}, this.theData, {
    /*      this getter seems to work ^^^^^^^^^^^^ */
      createData
    })
    console.log(newData) // looks good
    // set'ter new data
    this.theData(newData)
    return this
  }
  
  get theData() {
    return this.data
  }
  
  set theData(newData) {
    console.log('setting')
    this.data = newData;
  }
}
         
const Instance = new myClass('construct data')
  .create({createData: 'some data'})

But this gets the error

zakeyumidu.js:27 Uncaught TypeError: this.theData is not a function

at myClass.create

creating a non-setter method seems to work as I can just do

setTheData(newData) {
  this.data = newData // yep, that works
}

But I get the idea that getters/setters are preferred.

Is it okay to set instance data like this within class methods like my example that works? If not, why is my setter not working?

I'm trying to use getters and setters to adjust data initially set with a class constructor. The getter seems to work:

class myClass {
  constructor(sth) {
    this.data = {
      sth,
      timestamp: new Date()
    }
  }
  
  create(createData) {
    const newData = Object.assign({}, this.theData, {
    /*      this getter seems to work ^^^^^^^^^^^^ */
      createData
    })
    console.log(newData) // looks good
    // set'ter new data
    this.theData(newData)
    return this
  }
  
  get theData() {
    return this.data
  }
  
  set theData(newData) {
    console.log('setting')
    this.data = newData;
  }
}
         
const Instance = new myClass('construct data')
  .create({createData: 'some data'})

But this gets the error

zakeyumidu.js:27 Uncaught TypeError: this.theData is not a function

at myClass.create

creating a non-setter method seems to work as I can just do

setTheData(newData) {
  this.data = newData // yep, that works
}

But I get the idea that getters/setters are preferred.

Is it okay to set instance data like this within class methods like my example that works? If not, why is my setter not working?

• javascript
• ecmascript-6
• getter-setter

• is it pile time error ? – Pranay Rana Commented Mar 14, 2018 at 5:46

2 Answers 2

Instead of this.theData(newData) you should write this.theData = newData

class myClass {
  constructor(sth) {
    this.data = {
      sth,
      timestamp: new Date()
    }
  }

  create(createData) {
    const newData = Object.assign({}, this.theData, {
    /*      this getter seems to work ^^^^^^^^^^^^ */
      createData
    })
    console.log(newData) // looks good
    // set'ter new data
    this.theData = newData;
    return this
  }

  get theData() {
    return this.data
  }

  set theData(newData) {
    console.log('setting')
    this.data = newData;
  }
}

const Instance = new myClass('construct data')
  .create({createData: 'some data'})

this.theData(newData) would be accessing theData's getter. Since .data is not a function at the time that line executes (or ever), that is why you are getting that error.

To fix the problem, you should actually use the setter:

this.theData = newData;