JavaScript regex test if string contains a specific word (with variable)

Question

I have a regex to check if a string contains a specific word. It works as expected:

/\bword\b/.test('a long text with the desired word amongst others'); // true /\bamong\b/.test('a long text with the desired word amongst others'); // false 

But I need a word that needs to be checked in a variable. Using new RegExp does not work correctly, it always returns false :

 var myString = 'a long text with the desired word amongst others'; var myWord = 'word'; new RegExp('\b' + myWord + '\b').test(myString); // false myWord = "among"; new RegExp('\b' + myWord + '\b').test(myString); // false 

What is wrong here?

Answer 1

 var myWord = 'word'; new RegExp('\\b' + myWord + '\\b') 

You need to double escape \ when creating a regular expression from a string.

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This is because \ starts an escape sequence in a string literal, so it never gets into a regular expression. When you execute \\ , you include the literal character '\' in the string, which makes the regular expression /\bword\b/ .