Tips for utilizing the "this" keyword in JavaScript

Here's a snippet of code that I'm having trouble with:

this.json.each(function(obj, index) {
    var li = new Element('li');
    var a = new Element('a', {
        'href': '#',
        'rel': obj.id,
        events: {
            'click': function(e) {

                this.doSteps(this.step + 1); // <-- causing issue

            }
        }   
    });
    var img = new Element('img', {
        'src': imgd + obj.img,
        'alt': obj.name                        
    });
    img.inject(a);
    a.inject(li);
    li.inject(ul);
});

When running this code, I encounter an error message saying "this.doSteps is not a function" in the console. Any assistance and explanation on how to resolve this issue would be greatly appreciated.

Thank you very much for your help.

Answer №1

In order to ensure that the function's scope is correctly referring to the intended this, it is essential to bind this.

'click': function(e) {
    this.proceedToNextStep(this.currentStep + 1);
}.bind(this)

This method reflects the MooTools approach.

Answer №2

Consider encapsulating it in a function:

let list = new Element('li');
let _this = this;
let anchor = new Element('a', {
    'href': '#',
    'rel': objectIdentifier.id,
    events: {
        'click': function(event) {

            _this.executeTasks(_this.currentStep + 1);

        }
    }   
});

Answer №3

The problem is occurring on the specific line where this is pointing to the object that the function is a part of, in this case, it is referring to events. However, the object events does not contain any property named doSteps.

Answer №4

One way to utilize this is by including it in an each function with ,this.

this.json.each(function(object, position) {


    }, this);

Answer №5

Utilize the e element that is currently in use

this.json.each(function(obj, index) {
    var li = new Element('li');
    var a = new Element('a', {
        'href': '#',
        'rel': obj.id,
        events: {
            'click': function(e) {

                e.doSteps(e.step + 1); // <-- in this line, the 'e' from the function represents your element

            }
        }   
    });
    var img = new Element('img', {
        'src': imgd + obj.img,
        'alt': obj.name                        
    });
    img.inject(a);
    a.inject(li);
    li.inject(ul);
});

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