替换url中某个参数的值或是添加某个参数的方法(js 分页上下页可以使用)

function changeUrl(base, find, value) { 
    var offset = base.indexOf(find); 
    var index; 
    var rr = ''; 
    if(offset < 0){ 
        if(base.indexOf('?') < 0) { 
            base += '?'; 
        }else{ 
            base += '&'; 
        } 
        base += find + '=' + value; 
    }else{ 
        left = base.substr(0, offset); 
        right = base.substr(offset); 
        index = right.indexOf('&'); 
        if(index >= 0){ 
            rr = right.substr(index); 
        } 
        base = left + find + "=" + value + rr; 
    } 
    return base; 
} 
console.log(changeUrl('http://www.car.dev/?per_page=2&ano=3&dis=1', 'ano', 4));