What is the best way to account for the 'elvis operator' within a given expression?

When connecting to my data from Firebase, I noticed that using the elvis operator is essential to avoid encountering undefined errors. Recently, as I delved into creating reactive forms, I encountered an issue with a component I developed that fetches actual data from Firebase. The problem arises when working with the FormGroup, and here is a snippet of the code:

createForm() {
    this.quesForm = this.fbuild.group({
        question: this.featureQuestion.question,
        id      : this.featureQuestion.id,
        name    : this.featureQuestion.name,
        answers : this.fbuild.array([])
    });
    this.setAnswers(this.featureQuestion.answers);
}

Upon attempting to address the issue by including the elvis operator as shown below:

createForm() {
    this.quesForm = this.fbuild.group({
        question: this.featureQuestion?.question,
        id      : this.featureQuestion?.id,
        name    : this.featureQuestion?.name,
        answers : this.fbuild.array([])
    });
    this.setAnswers(this.featureQuestion?.answers);
}

I encountered additional errors indicating that an expression or punctuation such as ; and , was expected on every line. It became evident that simply adding the ? does not function the same way within the script compared to the template. How can I resolve this issue effectively?

Answer №1

Here is the proper way to use the ternary operator in JavaScript and TypeScript:

conditionToCheck ? valueIfTrue : valueIfFalse

In your specific scenario, you should implement it like this:

this.formData = this.formBuilder.group({
    question: this.selectedQuestion ? this.selectedQuestion.question : '',
    id      : this.selectedQuestion ? this.selectedQuestion.id : '',
    name    : this.selectedQuestion ? this.selectedQuestion.name : '',
    options : this.formBuilder.array([])
});

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