How do I make sure they don't get the same fact twice?

Question

How do I prevent the user from getting the same fact in a row?
```javascript
let factButton = document.getElementById('factButton'),
    factZone = document.getElementById('factZone'),
    DYK = document.getElementById('DYK'),
    facts = [
      'The average person walks the equivalent of three times around the world in a lifetime.', 'Coca-Cola would be green if coloring wasn’t added to it.', 'You cannot snore and dream at the same time.', 'New York drifts about one inch farther away from London each year.'  
    ];
function randomize() {
    var randomNumber = Math.floor(Math.random() * facts.length);
    console.log(randomNumber);
    factZone.innerHTML = facts[randomNumber];
}
randomize();
factButton.addEventListener('click', () => {
    randomize();
});
```

Steven Parker · Accepted Answer

:point_right: There are several ways to accomplish this, here are some options:
keep a separate array of booleans indicating which items have been used, re-pick until an unused item is selected
expand the data into an object array with both a string and "used" property for each, re-pick as above
move the picked item to the end of the list, then reduce the available choice size by 1
keep an entirely separate array for "picked" items, move each chosen one out of the source list to it
just delete each item that has been chosen (only if you do not need to re-use the list!)
I prefer the last three methods to the first two, because each random choice is guaranteed to return a unique item and no retries are needed.

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Joseph Frazer

Joseph Frazer

How do I make sure they don't get the same fact twice?

1 Answer

Steven Parker

Steven Parker

There are several ways to accomplish this, here are some options: