Replacing query string parameter values.

index.js

// Update the appropriate href query string parameter
function paramReplace(name, string, value) {
  // Find the param with regex
  // Grab the first character in the returned string (should be ? or &)
  // Replace our href string with our new value, passing on the name and delimeter
  var re = new RegExp("[\\?&]" + name + "=([^&#]*)"),
      delimeter = re.exec(string)[0].charAt(0),
      newString = string.replace(re, delimeter + name + "=" + value);

  return newString;
}

This is my preference, and it covers the cases I can think of. Can anyone think of a way to reduce it to a single replace?

function setParam(uri, key, val) {
    return uri
        .replace(new RegExp("([?&]"+key+"(?=[=&#]|$)[^#&]*|(?=#|$))"), "&"+key+"="+encodeURIComponent(val))
        .replace(/^([^?&]+)&/, "$1?");
}

/**

• 替换url参数
• @param {String} name 参数名
• @param {String} value 参数值
• @param {String} url 如果该值存在,则以该值为基准替换
  /
  function replaceUrlParam(name, value, newUrl) {
  let urlMark = '';
  let url = newUrl || location.href;
  let nameIndex = url.indexOf(name);
  //删除参数
  if (value === '') {
  //取当前参数前一位字符
  urlMark = url.charAt(nameIndex - 1);
  if (!/?|&/.test(urlMark)) {
  urlMark = '';
  }
  let reg = new RegExp("\" + urlMark + name + '=' + "[^&]");
  url = url.replace(reg, '');
  }
  //如果一个参数都没有
  else if (window.location.search === "" && new URL(location.href).searchParams.get(url) === '') {
  urlMark = '?';
  url = url + urlMark + name + '=' + value;
  }
  //有参数, 有当前参数
  else if (nameIndex > -1) {
  //这个urlMark 可能会是 ? 或 &
  urlMark = url.charAt(nameIndex - 1);
  let reg = new RegExp("\" + urlMark + name + '=' + "[^&]*");
  url = url.replace(reg, urlMark + name + '=' + value);
  }
  //有参数，但没有当前参数
  else if (nameIndex === -1) {
  urlMark = '&';
  url = url + urlMark + name + '=' + value;
  }
  //替换为正确的符号参数
  if (url.indexOf('?') === -1) {
  let matchParam = url.match('&');
  if (matchParam !== null) {
  url = url.replace(/&/, '?');
  }
  }
  return url;
  }

this is better

To replace all the query parameters with given value you can use something like this:

url.replace(/([?&])(((?![?&#=]).)*=)((?![?&#=]).)*/g, '$1$2xxx');