js合并并解决onload冲突

如何将一下两个js合并成一个并解决onload冲突问题

 <script>
    var a = 'aa';
    window.onload = function () { aaa}
</script>
<script>
    var b=’bb;’
    window.onload=function(){ bbb}
</script>

    window.onload = function () {
        var func = window.onload;
        if (typeof func == 'function') func();
        //...your code
    }

或者用attachEvent（IE）或者addEventListener（w3c浏览器）来添加onload事件