js正则验证url

function checkURL(URL) {
    var str = URL,
    Expression = /http(s)?:\/\/([\w-]+\.)+[\w-]+(\/[\w- .\/?%&=]*)?/,
    objExp = new RegExp(Expression);
    if(objExp.test(str) == true) {
       return true
    } else {
       return false
}