How to replace "?" or "&" from a string in Javascript

Question

How to replace "?test=666&test" to "222" in the following code?

If my code has "?" or "&", it will not work.

<body>
  hello
  <br>
  ?test=666&test

  <script>
    function rp (str, map) {
      for (var i in map) {
        str = str.replace(new RegExp(i, 'g'), map[i]);
      }
      return str;
    }

    document.body.innerHTML = rp(document.body.innerHTML, {
        'hello': '111',
        '?test=666&test': '222'
      });
  </script>
</body>

You escape them (and any other characters that have special meaning in the regex), more: stackoverflow.com/questions/3561493/… — T.J. Crowder
– T.J. Crowder, Commented May 16, 2018 at 10:54
? is wild char for Regex, You need to escape them if you want to use themselves in a string. Ex: ?test=666&test has to given like this, \?test=666\&test. As @PeterB said not sure about & char — Hassan Mudassir
– Hassan Mudassir, Commented May 16, 2018 at 10:55
You need to use \\? in the string. This way the string will contain \?. Only this will work in the RegExp constructor. — Sebastian Simon
– Sebastian Simon, Commented May 16, 2018 at 11:06
Possible duplicate of escaping question mark in regex javascript — Sebastian Simon
– Sebastian Simon, Commented May 16, 2018 at 11:07

T.J. Crowder · Accepted Answer · 2018-05-16 11:08:34Z

0

? and & and several other characters have special meaning in regular expressions. You need to escape them (with a \) to use them literally.

This question's answers describe doing so in the general case.

Using a hypothetical escapeRegex function derived from those answers, you'd do:

str = str.replace(new RegExp(escapeRegex(i), 'g'), map[i]);

To just handle ? and &, you'd do this (but don't do this, it leaves the door open for other special chars):

str = str.replace(new RegExp(i.replace(/[?&]/g, "\\$&")., 'g'), map[i]);

answered May 16, 2018 at 11:08

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T.J. Crowder

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1 Comment

Ken.c Over a year ago

str = str.replace(new RegExp(escapeRegex(i), 'g'), map[i]); this is not work . could you help me again?

Peter B · Accepted Answer · 2018-05-16 11:11:18Z

0

You need to take care of escaping and encoding in various different ways:

In regex, ? is a modifier. You need to escape it and use \? instead.
In a javascript string literal, \ is a special character. To get a single backslash in a string you need to write '\\', and to get \? in a string you need to write '\\?'
In HTML, a simple & translates to &. To match that encoded character, you need to look for &

This is the result of what you should use:

function rp(str, map) {
  for (var i in map) {
    str = str.replace(new RegExp(i, 'g'), map[i]);
  }
  return str;
}
document.body.innerHTML = rp(document.body.innerHTML, {
  'hello': '111',
  '\\?test=666&amp;test': '222'
});

<body>
  hello
  <br>
  ?test=666&test
</body>

answered May 16, 2018 at 11:11

Peter B

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1 Comment

Ken.c Over a year ago

thanks. it's cool. and i want another way. i want to change my code , not change the ?test=666&test. thanks a lot.

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