How to give parameters to an specific object in an array

I have an array with objects. Now I want to find some of them and give them different parameters. Like, all the objects that are < 1900 should be yellow.

I have already tried to make a funktion with an if- statement. I want to have a function, so later I can use the functionname in the .attr{(...),}

function init() {
    paper = Snap("#svgContainer");
    for (i = 0; i < data.length; i++) {
        data[i].circle = paper.circle(0, 0, 1);
    }


    function Years() {
        for (var i = 0; i < data.length - 0; i++) {
            xPos = map(data[i].longitude, (0 - 180), 180, 0, paperWidth);
            yPos = paperHeight - map(data[i].latitude, (0 - 90), 90, 0, paperHeight);

            function color() {
                if (data.year > 0 && < 1000) {
                    circleColor = "black"
                } else if (data.year > 1000 && < 1500) {
                    circleColor = "red"
                } else {
                    circleColor = "orange"
                }
            }

            data[i].circle.animate({
                cx: xPos,
                cy: yPos,
                fill: color,
                r: 5,
            }, 50);
        };

I may have did something wrong with the function. The console logs "SyntaxError: expected expression, got '<'" or the same with "..., got 'if'"