単純に引数で渡すとか。。。
index.html
lang
1<!DOCTYPE html>
2<html>
3<body>
4<script>
5var s= "yes!";
6function button_click() {
7 window.open("./child.html?s=" +s);
8}
9</script>
10<button onclick='button_click();'>Hint</button>
11</body>
12</html>
child.html
lang
1<!DOCTYPE html>
2<html>
3<body>
4<script>
5s = location.search;
6s = s.substring(1,s.length);
7document.write(s);
8</script>
9</body>
10</html>
2015/02/17 01:23