Remove duplicate item from array Javascript [duplicate]

Answer 1

You can use Array.reduce() to remove the duplicates. You need a helper object to keep track of how many times an item has been seen.

function cleanUp() 
{
    var textBox = document.getElementById("fld"),
    array = textBox.value.split(/\r?\n/g),
    o = {},
    output;

    output = array.reduce(function(prev, current) {
        var key = '$' + current;

        // have we seen this value before?
        if (o[key] === void 0) {
            prev.push(current);
            o[key] = true;
        }

        return prev;
    }, []);

    // write back the result
    textBox.value = output.join("\n");
}

The output of the reduce() step can be used directly to populate the text area again, without affecting the original sort order.

Demo