test.html

<html>
<title>AtCoder Rating Estimator</title>
<body>
<script language="javascript" src="atcoder_rating.js"></script>
<script language="javascript">

function calc(arr, goal_rating) {
	// binary search
	goal_rating = unpositivize_rating(goal_rating)
	var lo = -10000.0;
	var hi = 10000.0;
	for (var i = 0; i < 100; ++i) {
		var mid = (hi + lo) / 2;
		var r = calc_rating([mid].concat(arr));
		if (r >= goal_rating) {
			hi = mid;
		} else {
			lo = mid;
		}
	}
	return hi;
}

function keydown_enter() {
    if(window.event.keyCode == 13) {
        document.getElementById("calculate").click();
    }
}


function calculatePerformance() {
	var past_perf = document.getElementById("past_performances").value;
	var arr = [];
	if (past_perf == "") {
		arr = [];
	} else {
		arr = past_perf.split(/\r\n|\r|\n/);
		for (var i = 0; i < arr.length; ++i) {
			arr[i] = parseInt(arr[i], 10);
		}
	}
	var goal_rating = document.getElementById("goal_rating").value;
	goal_rating = parseInt(goal_rating, 10);
	document.getElementById("goal_performance").textContent = 
		calc(arr, goal_rating).toString();
}
</script>

<p>過去のパフォーマンス(1行に1個ずつ、新しいのが上)
<textarea id="past_performances" cols="6" rows="20"></textarea></p>
<p>目標レーティング<input type="text" id="goal_rating" onkeydown="keydown_enter();"></p>
<p>必要なパフォーマンス<div id="goal_performance">5000兆</div><p>
<button id="calculate" onclick="calculatePerformance();">計算する</button>

</body>
</html> 