How to create 2 `this` link in javascript from inside function

Question

I'm having trouble working my code as I try to break it into smaller methods due to the link this. My code is as follows:

const pageObject = {

    /* set listener to get id of the radio input and then do something with it*/
    onChange() {

        // `this` here refers to the pageObject
        console.log(this);

        $('.radio input[type="radio"]').on('click', function() {

              // `this` here refers to the radio input
              console.log(this);

              let $id = $(this).data('id');

              // Error because `this` is referencing the radio input and not the pageObject.
              this.doSomething($id); 
        }

    },

    /* just does something */
    doSomething($id) {
        return ... 
    }

}

// just calls the method on object so we can get started
pageObject.onChange();

I also want to avoid using esc arrow-functions () =>and self = thismethods, if possible, as recommended in YDKJS: This and Object Prototypes .

Is there a way for a .bind()/.call()/.apply()method onChange()to refer to thiswhich refers to pageObj, as well as to thiswhich refers to the radio?

Feel free to change the code if necessary. Thank you, look forward to!

Update

Thanks event.target, as suggested below, here is a working block of code:

const pageObject = {

    /* set listener to get id of the radio input and then do something with it*/
    onChange() {

        // `this` here refers to the pageObject
        console.log(this);

       let radioHandler = function radioHandler(event) {

              // `this` here also refers to the pageObject too since we are about to call this function via .bind()
              console.log(this);

              // use event.target here instead. sweet stuff.
              let $id = $(event.target).data('id');

              // doSomething() now works!
              this.doSomething($id); 
        }

        $('.radio input[type="radio"]').on('click', radioHandler.bind(this));

    },

    /* just does something */
    doSomething($id) {
        return ... 
    }

}

// just calls the method on object so we can get started
pageObject.onChange();

Update 2

this ?, @gyre , ​​ , this, , event.target. , MDN Docs Event.target

Answer 1

- .

const pageObject = {

    /* set listener to get id of the radio input and then do something with it*/
    onChange() {

        // `this` here refers to the pageObject
        console.log(this);
        const self = this;

        $('.radio input[type="radio"]').on('click', function() {

              // `this` here refers to the radio input
              console.log(this);

              let $id = $(this).data('id');

              // Error because `this` is referencing the radio input and not the pageObject.
              self.doSomething($id); 
        };

    },

    /* just does something */
    doSomething($id) {
        return ... 
    }

}

// just calls the method on object so we can get started
pageObject.onChange();

this , event.target, :

const pageObject = {

    /* set listener to get id of the radio input and then do something with it*/
    onChange() {

        // `this` here refers to the pageObject
        console.log(this);

        $('.radio input[type="radio"]').on('click', (event) => {

              // `this` here refers to the radio input
              console.log(event.target);

              let $id = $(event.target).data('id');

              // Error because `this` is referencing the radio input and not the pageObject.
              this.doSomething($id); 
        };

    },

    /* just does something */
    doSomething($id) {
        return ... 
    }

}

// just calls the method on object so we can get started
pageObject.onChange();

...

const pageObject = {

    /* set listener to get id of the radio input and then do something with it*/
    onChange() {

        // `this` here refers to the pageObject
        console.log(this);

        $('.radio input[type="radio"]').on('click', this.onRadioClick.bind(this)) ;

    },

    onRadioClick(event) {

            // `this` here refers to the radio input
            console.log(event.target);

            let $id = $(event.target).data('id');

            // Error because `this` is referencing the radio input and not the pageObject.
            this.doSomething($id); 
    },

    /* just does something */
    doSomething($id) {
        return ... 
    }

}

// just calls the method on object so we can get started
pageObject.onChange();

Answer 2

event.target event.currentTarget . javascript ) .on().

$('.radio input[type="radio"]').on('click', function(event) {

  // `this` here refers to the radio input
  let $id = $(event.target).data('radioId');

  // Error because `this` is referencing the radio input and not the pageObject.
  this.doSomething($id); 
})

Answer 3

. : .

, , , . ,

const pageObject = {

    /* set listener to get id of the radio input and then do something with it*/
    onChange() {

        const parent = this
        // 'parent and `this` here both refer to the pageObject
        // 'parent' masks an instance of 'this' which can be accessed via closures
        console.log('parent, this: ', parent, this);

        $('.radio input[type="radio"]').on('click', function() {

            // `this` here refers to the radio input
            console.log(this);

            let $id = $(this).data('id');

            // 'parent' accesses parent 'this' thanks to closures and masking 
            parent.doSomething($id); 
        }

    },

    /* just does something */
    doSomething($id) {
        return ... 
    }

}

// just calls the method on object so we can get started
pageObject.onChange();

bind. , eventListener , , , 'this' , . , .

:

const pageObject = {

    /* set listener to get id of the radio input and then do something with it*/
    onChange() {

        // `this` refers to the pageObject
        console.log(this);

        // creates radio onClick eventListener
        // assigns handleRadio function as event handler
        // binds pageObject 'this' context for use in event handler
        $('.radio input[type="radio"]').on('click', this.handleRadio).bind(this);
    },

    // separated event handler function to show how this works in more modular code.
    handleRadio(e) {
        // use e.target to give you the context for the click event
        // use 'this' to access the pageObject 'this' context
        console.log('e.target, this: ', e.target, this);

        // still accesses pageObject 'this' due to the eventListener bind
        let $id = $(this).data('id');

        // No error
        this.doSomething($id); 
    },

/* just does something */
doSomething($id) {
    return ... 
}

}

// just calls the method on object so we can get started
pageObject.onChange();