Use variable to replace all occurrences of specific string

Question

How do I use a dynamic variable as first argument in replace function?

I have this code that searches a user specified string:

 var query = jQuery.trim(jQuery(this).val()).toLowerCase();
 console.log(query + ' was searched')
 jQuery('.one-reference').each(function () {
    var jQuerythis = jQuery(this);
    if (jQuerythis.text().toLowerCase().indexOf(query) === -1) {
       jQuerythis.fadeOut();
    }
    else {
       jQuerythis.html(jQuerythis.html().replace(/&/g, '<strong>$&</strong>'));
       jQuerythis.fadeIn();
    }
 });

This replace(/&/g, '<strong>$&</strong>')) is not working.

I want to wrap all occurrences of query with <strong> tags.

@Stefan it will search for the sting query then ... not the string inside variable it will search for — Umair Ayub
– Umair Ayub, Commented Nov 28, 2016 at 14:50
FYI: your problem is unrelated to jQuery. String.prototype.replace is a standard JavaScript function. — Phrogz
– Phrogz, Commented Nov 28, 2016 at 15:26

John C · Accepted Answer · 2016-11-28 15:29:16Z

3

As you're searching for an arbitrary value within the html you will need to create a RegExp object and use that in your replace.

if (jQuerythis.text().toLowerCase().indexOf(query) === -1) {

  jQuerythis.fadeOut();
} else {
  var queryReg = new RegExp(query, 'g');
  jQuerythis.html(jQuerythis.html().replace(queryReg, '<strong>$&</strong>'));
  jQuerythis.fadeIn();
}

Also you will first need to escape (\) any characters in your query variable that have a special meaning in regular expressions (^$[]+()\/- for example) -

query = query.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');

(from MDN)

See Regular Expressions at Mozilla Developer Network for a more in depth discussion on regular expressions.

edited Nov 28, 2016 at 15:29

answered Nov 28, 2016 at 14:53

John C

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2 Comments

Stefan Over a year ago

Be sure to mention that inputting + or [] as parts of the query will mess around with the regex if they're not properly escaped.

Shil Nevado Over a year ago

He could also use a function to clean the string query like: function replaceScapeChar(value) { return value.replace(/([\[|\]|\||$|$|\.|\*|\+|\{|\}|\$])/g, "\\$1") } (Maybe I didn't write ALL the scape characters. Add what I forgot :P)

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