Variable WITH Regex (Javascript)

Question

I know there are many questions answered with this title but I have not found any that fit what I'm looking for...

I need to use regex like this "/^ user input $/i" The user input can put the * regex character in front of or behind the text.

If I use the "new RegExp(user input, "i")" does not accomplish the requirements of ^ and $ and the user regex character *.

I had something like this:

var foo = {User input};

var arr = ['Lorem Ipsum', 'simply dummy text', 'nothing'];

arr = arr.filter(function(item){
     return /^{foo content here}$/i.test(item);
});

Tests:

foo = "Lorem" -> array[]
foo = "Lorem*" -> array['Lorem Ipsum']
foo = "Dummy" -> array[]
foo = "*Dummy*" -> array['simply dummy text']
foo = "*" -> array['Lorem Ipsum', 'simply dummy text', 'nothing']

Many thanks.

`If I use the "new RegExp(user input, "i")" does not accomplish the requirements of ^ and $` then do `new RegExp("^" + userInput + "$", "i")`. `and the user regex character *` - what is this? — VLAZ, Dec 28 '16 at 11:51
To simplify I have an array of names and the user performs an exact search on the one unless it uses the regex character "*" — user7349564, Dec 28 '16 at 11:57
What do you mean by "regex character `*`"? A quantifier or a wildcard `*`? — Wiktor Stribiżew, Dec 28 '16 at 11:57
@Fallenhero: That is only when `*` must be treated as a wildcard. Also, other special regex chars should be escaped then. — Wiktor Stribiżew, Dec 28 '16 at 11:58
@WiktorStribiżew i think thats what OP means. Like the wildcard in DOS — Fallenhero, Dec 28 '16 at 11:59
Then, the solution is really simple. Split with `*`, escape all special chars in the array items, join with `.*`. — Wiktor Stribiżew, Dec 28 '16 at 12:00
Try [`return new RegExp("^" + foo.split("*").map(function (x) { return x.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&') }).join(".*") + "$", "i").test(item)`](https://jsfiddle.net/e1j19dq5/). — Wiktor Stribiżew, Dec 28 '16 at 12:09
Yes, is a wildcard and I need to replace the `*` with `.*` but how can I use the user string with `.*` in the .test() with the `^` begin and `$` end and the `i` for case-insensitive ¿? — user7349564, Dec 28 '16 at 12:09
You accepted some other solution, so you do not need wildcards. — Wiktor Stribiżew, Dec 28 '16 at 12:17

KooiInc · Accepted Answer · 2016-12-28T14:18:30.920

You can use '^' + foo + '$', but you should prevent invalid regular expressions as a result. Something like:

var arr = ['Lorem Ipsum', 'simply dummy text', 'nothing'];

function userInput(foo) {
  var re = null;
  try { 
    re = /[*+.]/.test(foo) 
      ? RegExp(foo, 'i') 
      : RegExp('^' + foo + '$', 'i'); }
  catch(err) { 
    return '<i style="color:red">' + err.message +'</i>'; 
  }
  var filtered = arr.filter(function(item){ return re.test(item); });
  return filtered.length 
    ? '<b style="color:green">[' + filtered.join() + ']</b>' 
    : '<b style="color:orange">*nothing found*</b>'
}

document.querySelector('#result').innerHTML =
  'Lorem -> ' + userInput('Lorem') + '\n' +
  'Lorem* -> ' + userInput('Lorem*') + '\n' +
  '*Lorem* -> ' + userInput('*Lorem*') + '\n' +
  'Dummy -> ' + userInput('Dummy') + '\n' +
  '*Dummy.* -> ' + userInput('*Dummy.*') + '\n' +
  '.*Dummy -> ' + userInput('.*Dummy') + '\n' +
  '* -> ' + userInput('*') + '\n' +
  '+ -> ' + userInput('+') + '\n' +
  'd.+ -> ' + userInput('d.+') + '\n' +
  'ips.+$ ->' + userInput('ips.+$') + '\n' +
  'ip.m ->' + userInput('ip.m') + '\n' +
  'i*mp ->' + userInput('i*mp') + '\n' +
  '.* -> ' + userInput('.*');

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Variable WITH Regex (Javascript)

1 Answers1