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JavaScript JavaScript Loops, Arrays and Objects Tracking Multiple Items with Arrays Build a Quiz Challenge, Part 2 Solution

Posted by J V
J V
3,414 Points

Trying to review the code for better understanding Two-Dimensional Arrays

I am just trying to review the code for better understanding in relation to how the code is displayed on the screen:

Below is a small portion of code form the Build a Quiz using Two-Dimensional Arrays:

HTML = "You got these answers correct: " + correctQ + "<br>";
HTML += "<h2>You got these questions correct: </h2>";
HTML += buildList(rightQuestions);

HTML += "<h2>You got these questions incorrect: </h2>";
HTML += buildList(wrongQuestions);

Is it accurate to say the above code is the same as this code below (refer to code that is not commented out): 

/*Writing the code out for visualization
HTML = "You got these answers correct: " + correctQ + "<br>";

HTML = HTML + "<h2>You got these questions correct: </h2>";
HTML = HTML + buildList(rightQuestions);

HTML = HTML + "<h2>You got these questions incorrect: </h2>";
HTML = HTML + buildList(wrongQuestions);
*/


HTML = "You got these answers correct: " + correctQ + "<br>";
HTML =  "You got these answers correct: " + correctQ + "<br>" +
               "<h2>You got these questions correct: </h2>";

HTML = "You got these answers correct: " + correctQ + "<br>" + 
              "<h2>You got these questions correct: </h2>" +
              "<ol>" + "<li>" + array[i] + "</li>" + "</ol>";


HTML = HTML + "<h2>You got these questions incorrect: </h2>";

HTML = "<h2>You got these questions incorrect: </h2>" + 
             "<ol>" + "<li>" + array[i] + "</li>" + "</ol>";

Also, is there an easier way to display all of this code instead of writing HTML += ..etc?

2 Answers

Jacob Mishkin
Jacob Mishkin
23,118 Points
Jacob Mishkin
Jacob Mishkin
23,118 Points

The two examples are not the same at all, due to the assignment operators used "+=" and "=". In the first example by using the += operator you are adding the value right of the operator into the variable in other words concatenating into the variable. In the second example you are using just the "=" operator. By doing this you are not adding the value, rather you are just assigning a new value to the variable, not concatenating them.

I hope this helps.

I'm not sure about anything better than using the += operator except a using a loop perhaps.

if you want to learn more check this out:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Assignment_Operators#Addition_assignment

J V
J V
3,414 Points
J V
J V
3,414 Points

Hi Jacob,

Thank you for your input. I appreciate it. Thanks for the reference link as well. :)