Javascript: ¿cómo podemos recuperar parámetros de QueryString?

<script type="text/javascript">
function getQueryStringVariable(variable) {
var query = window.location.search.substring(1);
var vars = query.split("&");
for (var i = 0; i < vars.length; i++) {
var pair = vars[i].split("=");
if (pair[0].toLowerCase() == variable.toLowerCase()) {
return pair[1];
}
}
}
var myTextField = document.getElementById('myText');
myTextField.value = getQueryStringVariable("myQuerystringname");
</script>