How do I use a variable to find an element in an array?

Question

I'd like to take some user input and use it to find a certain object in an array. But when I try to do it with the code below, I get an undefined error. What am I doing wrong?

function findNextLevel() {
    var currentLevel = parseFloat(document.getElementById("currentLevel").value);
    var xpForLevel = trainerLevels.currentLevel;
    document.getElementById("result01").innerHTML = xpForLevel;
}

If you are using a variable to get the value of a property, you have to use the bracket notation: `var xpForLevel = trainerLevels[currentLevel];` — Gerardo Furtado, Jul 31 '16 at 09:03
Quite well discussed in the [documentation](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Operators/Property_accessors). — , Jul 31 '16 at 09:29

score 1 · Accepted Answer · answered Jul 31 '16 at 09:06

I'm assuming that trainerLevels is an array and currentLevel is an index. If so, the way to access an element in an array at a certain index is to use brackets like so. Otherwise, could you provide more details in your question?

var xpForLevel = trainerLevels[currentLevel];

If this is the answer that you were looking for, then may I recommend that you use the parseInt rather than the parseFloat function for getting the index? And also, since it is user input, you may want to check that currentLevel is in the correct range as well.

How do I use a variable to find an element in an array?

1 Answers1