RegExp search for special character "[" [duplicate]

This question already has answers here: 开发者_Python百科 Is there a RegExp.escape function in JavaScript? (18 answers) Closed 4 years ago.

I'm having difficulty scanning for the special character "[". After looking around, I've tried:

var regEx = new RegExp(someValue + "[\x5B]");  // "5B" is the hex-value for "["

(I DO want case-sensitivity and I ONLY want the first occurrence so I intentionally didn't add any modifiers.)

I have been looking and looking, and I still have no idea what I'm doing wrong. If this is a bone-headed question, I'm sorry, but I'm new to JavaScript, and I'm still learning all the ins and outs.

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function escapeRegExp(str) {
  return str.replace(/[-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, "\\$&");
}

var re = new RegExp(escapeRegExp(str));   

See: Escape string for use in Javascript regex

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var regEx = new RegExp(someValue + "\\[");

You simply have to escape it with a backslash. The backslash is double because it is a javascript special character as well.

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Should be fine, if you just escape the character:

new RegExp(someValue + "\\[");

You need two backslashes because the backslash is the escape character for strings too. So \\[ will result in the string \[ which is what we need.

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Both the regex .\[ and .[\x5B] match the sub-string "e[" from the text:

"some[text"

as you can see yourself:

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http://ideone.com/iR78l

var text = "some[text";
print(text.match(/.\[/));

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and http://ideone.com/qvsCz

var text = "some[text";
print(text.match(/.[\x5B]/));

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I think all you need is /[/ for your expression to find the first occurrence of "["

If there's something more complicated you're looking for, check out this tool: http://www.gskinner.com/RegExr/

It's a life-saver for creating regular expressions.