Question

I tried to write some javascript that takes the entries of an array and shuffles the order. It’s not compiling like it should though. Seems to only run through the for loop once. What am I missing?

//random number between 1 and num
function randInt(num){
    return Math.floor(num*Math.random()+1);
}

//shuffles deck (array) of any size
function shuffle(array){
    var newArray = new Array();
    var n = array.length;
    for(i=0; i<n; i++){
        var entry = randInt(array.length) - 1;
        newArray[i] = array[entry]; //assigns random entry in initial array to       new array
            array = array.splice(entry, 1); //removes the entry that was stored into newArray
    }
    array = newArray;
}

Answer 1

• array.splice modifies array and returns the removed item(s). You want to discard the element, so just do this instead of overwriting array:

array.splice(entry, 1);

• + 1 in randInt and doing - 1 afterwards seems superflouous.
• Use var i = 0 (though look at my last point).
• Use [] instead of new Array() since the latter is not generally used.
• Return the new array instead of overwriting array:

return newArray;

• You modify array so you cannot loop up to n anymore as the length becomes 1 less each time. You may want while(array.length > 0) { ... } instead of the for loop.