SOURCE

let url = 'http://plm.lanxincn.com:8557/?code=CKcdOExYMr4N6Tz35obe7nCqlYu7wvXObKvxYMvFMUw&state=1%23wechat_redirect#/%2Fentry%3FentryType%3Dhome';
let string1 = 'code=CKcdOExYMr4N6Tz35obe7nCqlYu7wvXObKvxYMvFMUw&state=1%23wechat_redirect'
let string2 = 'code=G8qCeMSP_7qi8FlKWEgZTLpXIE4innBJ9GCiUpBIV8k&state=1%23wechat_redirect'
function getQueryString(name='code') {
  const reg = new RegExp('(^|&)' + name + '=([^&]*)(&|$)', 'i');
  const result = string1.match(reg);
  if (result != null) {
    return decodeURIComponent(result[2]);
  }
  return null;
}

console.log(getQueryString())