获取url参数

获取url参数。

const getUrlParam = function(param_name) {
    var reg = new RegExp("(^|&)" + param_name + "=([^&]*)(&|$)");
    var r = window.location.search.substr(1).match(reg);
    if (null != r) return unescape(r[2]);
    return null;
}

// url: https://www.baidu.com/s?wd=%E5%AD%97%E6%AE%B5&rsv_spt=1&rsv_iqid=0xd0b8cedf0003ddd6&issp=1&f=8&rsv_bp=1&rsv_idx=2&ie=utf-8&rqlang=cn&tn=baiduhome_pg&rsv_enter=1&rsv_dl=tb&rsv_btype=t&inputT=1124&rsv_t=5d5fy7IgBRPdzAzH14Trm1rHQHMc7tyfekRowuJWwzCd44xNsWtYNcwkvDVBRPAttnsv&rsv_sug3=11&rsv_sug1=7&rsv_sug7=100&oq=get&rsv_pq=f54d93940005c478&rsv_sug2=0&rsv_sug4=5075
getUrlParam('wd');
// "字段"