Javascript score target alert

New to JS, please be nice.

In creating a Javascript score for a browser canvas game, the code below increases by 1 for each second. For the variable score to equal 100, how would I go about this function displaying a window alert for when it reaches this value?

Attempts similar to if(score == 100), alert(score) have not worked for me.

Below code will not currently work in JSFiddle, output displays in browser tab.

var start = new Date().getTime(),
    score = '0.1';

window.setInterval(function() {
    var time = new Date().getTime() - start;
    score = Math.floor(time / 1000) ;
    if(Math.round(score) == score) 
        { score += '.0 Score'; }
    document.title = score;
}, 100);