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JavaScript

Posted by Greg Schudel
Greg Schudel
4,090 Points

Syntax Question about grabbing Keys of an object

I'm taking a course where I am being asked this question:

If I had the key of "created at" how would I access the value of that property on an object?

The correct answer is blogPost["created at"];

This makes ZERO sense to me when I just made a project that called the key of an using this:

QuizUI.displayNext();

the complete object looked like this:

var QuizUI = {

    // I am compleletly lost at this syntax, NEVER seen it before in my life, 
    //is this an array with a function as the key of each value?
    displayNext: function(){
        if (quiz.hasEnded()) {
            this.displayScore();
        }else {
            // this updates all parts of the UI
            this.displayQuestion();
            this.displayChoices();
            this.displayProgress();
        }

    },
    displayChoices: function(){
        this.populateIdWithHTML("question", quiz.getCurrentQuesiton().text);

    },
    displayChoices: function(){
        var choices = quiz.getCurrentQuestion().choices;

        for(var i = 0; i < choices.length; i++){
            this.populateIdWithHTML("choice" + i, choices[i]);
            this.guessHandler("guess" + i, choices[i]);
        }

    },

    displayScore: function(){
        var gameOverHTML = "<h1>Game Over</h1>";
        gameOverHTML += "<h2> Your score is: " + quiz.score + "</h2>";
        this.populateIdWithHTML("quiz", gameOverHTML);
    },

    populateIdWithHTML: function(id, next) {
        var element = document.getElementById(id);
        element.innerHTML = text;

    },

    guessHandler: function(id, guess){
        var button = document.getElementById(id);
        button.onclick = function(){
            quiz.guess(guess);
            QuizUI.displayNext();
        }
    },

    displayProgress: function(){
        var getCurrentQuestion = quiz.currentQuestionIndex + 1;
        this.populateIdWithHTML("progress", "Question" + currenyQuestionNumber + " of " + quiz.questions.length);
    }


}

what am I not understanding about this syntax?

2 Answers

Steven Parker
Steven Parker
243,200 Points
Steven Parker
Steven Parker
243,200 Points

The word "called" is a clue indicating the difference between a property and a method. In your example you are calling a method of an object, but the original question was about accessing the value of a property.

Also the "dot" notation you used to get to your method would also normally be used with properties, but not if the key contains a space. That's why the bracket notation is necessary for this particular property.

Greg Schudel
Greg Schudel
4,090 Points

but wouldn't I use this one? blogPost"created at";

Isn't this correct syntax or am I confusing that with something else?

Steven Parker
Steven Parker
243,200 Points
Steven Parker
Steven Parker
243,200 Points

You still need the brackets. In JavaScript, it's never correct to place a literal string next to another identifier.

Greg Schudel
Greg Schudel
4,090 Points
Greg Schudel
Greg Schudel
4,090 Points

Thank you thank you thank you thank you!!!!