如何在递归之前从数组中删除某个元素？

Question

So I'm trying to make a basic bomb wire cutting game where you get 4 randomly picked colors from an array of 6 possible colors, but I'm having trouble with getting it so there are no duplicate colors in the 4 random colors. I'm not sure how to remove already picked colors from the array. I think my logic is wrong.

const colors = ['Blue', 'Red', 'Yellow', 'White', 'Black', 'Green']
function getXRandomColors(colors, x, result) {
    if (x === 0) return result
    const randomIndex = Math.floor(Math.random() * colors.length)
    if (colors.includes(randomIndex)){
        colors = colors.filter(color => color !== randomIndex)}
    return getXRandomColors(colors, x - 1, [...result, colors[randomIndex]])
}
var fourRandomColors = getXRandomColors(colors, 4, [])
console.log('The wires are: ' + fourRandomColors);

Answer 1

I'd create a temporary variable set to the picked color, then removing that array entry at the randomIndex before continuing recursion.

const colors = ['Blue', 'Red', 'Yellow', 'White', 'Black', 'Green']
function getXRandomColors(colors, x, result) {
    if (x === 0) return result
    const randomIndex = Math.floor(Math.random() * colors.length)
    let pickedColor = colors[randomIndex];
    colors.splice(randomIndex, 1);
    return getXRandomColors(colors, x - 1, [...result, pickedColor])
}
var fourRandomColors = getXRandomColors(colors, 4, [])
console.log('The wires are: ' + fourRandomColors);

This way you are guaranteed there won't be any duplicates.

Couple things that are going wrong in your current example:

In your filter function

    colors = colors.filter(color => color !== randomIndex)}

The condition ( color !== randomIndex ) will always be true, because random index is a number and color is a string. What you'd want to do if you'd compare index is;

    colors = colors.filter((color, index) => index !== randomIndex)}

But even this won't have the desired result , since you're removing the random index from your array without storing it somewhere, this is how duplicates will show up in the first place.