Encountered an error trying to access an array element by index stored in a variable within Vue.JS,

It appears that I have encountered a bug in my code. My intention is to retrieve components objects by index (for the tag), but I am facing an unusual issue. Details of the problem can be seen below:

Successful scenario:

let steps = ['Handler', 'Categories', 'Finalize'];
export default {
    components: {
        Handler,
        Categories,
        Finalize
    },

    data() {
        return {
            step: 0,
            currentStep: steps[0] // Accessing component using direct index 
        }
    },

}

Error scenario:

let steps = ['Handler', 'Categories', 'Finalize'];
export default {
    components: {
        Handler,
        Categories,
        Finalize
    },

    data() {
        return {
            step: 0,
            currentStep: steps[this.step] // Accessing component using a variable as index 
        }
    },
}

In the successful example, I successfully retrieved the component, however, in the error scenario, Vue DevTools displays currentStep: undefined. Strangely, there are no console errors present. What could be going wrong?

Answer №1

The most effective approach would be to move the currentStep to a computed property. Ensure that the steps are included in the data so they can react accordingly:

let steps = ['Handler', 'Categories', 'Finalize'];
export default {
    components: {
        Handler,
        Categories,
        Finalize
    },

    data() {
        return {
            step: 0,
            steps,
        }
    },
    computed: {
      currentStep() {
        return this.steps[this.step];
      }
    }
}

If possible, it's best to directly include the steps in the data:

data() {
    return {
        step: 0,
        steps: ['Handler', 'Categories', 'Finalize'];,
    }
},

(However, this may not be feasible if they are imported externally. This depends on your specific use case).

In Vue, it is generally recommended to use computed properties when a component's behavior relies on the value of certain properties for improved performance and clarity.

In your original code snippet, using a computed property ensures that the currentStep updates whenever the step changes, unlike before where it would not react accordingly.

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