Javascript: Brackets after an array in braces [duplicate]

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• understanding decision table in javascript 2 answers

I've just run into a piece of code I've never seen before, and can't find an explanation anywhere online:

function segColor(c) {
    return {
        red: "#FF0000",
        green: "#00ff00",
        blue: "#0000ff"
    }[c];
}

What operation is being done to the function parameter c? What does {array}[val] do in javascript? Searching for "brackets after braces" doesn't really reveal a lot.

via Chebli Mohamed