Javascript regular expression to remove double backslashes

Question

Having some trouble with backslashes regular expressions. I want to remove all dual backslashes (or any multiple of 2) that exist on any string property of an object. I do not want to remove single backslashes nor the last backslash in an odd number of backslashes (e.g., leave one backslash remaining in a set of five continuous backslashes \\\\\ -> \).

The code is here:

http://jsfiddle.net/59Zau/

//removes all dual backslahes on all string properties on an object
var removeDualBackslash = function (obj) {
    var ret = null;
    if (typeof(obj) == "string") {
        obj = obj.replace(/\\\\/g,"");
        return obj;
    } else if (typeof(obj) == "number") {
        return obj;
    } else if (typeof(obj) == "array") {
        ret = [];
    } else {
        ret = {};
    }
    for (var key in obj)
        ret[key] = removeDualBackslash(obj[key]);
    return ret;
};

var oJSON = {"t4m_data_in":{"no_data":"No data \\passed in."}};

oJSON = removeDualBackslash(oJSON);

console.log(oJSON.t4m_data_in.no_data);

As you can see from the console.log, one of the backslashes remains. Does anyone know what regular expression I need to remove both of them?

hugomg · Accepted Answer · 2013-10-16 18:08:19Z

6

The problem is in your JSON string. The "\\" there is already a single backslash.

>> console.log("No data \\passed in");
No data \passed in

Are you sure you don't want to just remove all backslashes instead?

obj = obj.replace(/\\/g,"");

Doing so would remove literal backslashes like "\\" but would still preserve other escape sequences like "\n" because in those cases the backslash is just in the string literal, not in the actual string.

edited Oct 16, 2013 at 18:08

answered May 30, 2012 at 22:57

hugomg

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4 Comments

Elliot B. Over a year ago

Makes sense--I suppose then I could just do obj = obj.replace(/\\/g,""); because any backslash present in the string at the time of .replace was originally dual backslash.

Elliot B. Over a year ago

Well, this function will eventually get applied strings that contain escaped JSON... that's where my headache multiplies. I think this will work though, I'll accept this answer, thanks!

hugomg Over a year ago

@ElliotB: Why do you even need to replace backslashes? Ideally you should not even have to do this...

Elliot B. Over a year ago

I'm working with a proprietary backend whose native method to convert JSON to record structure errors when two or more consecutive backslashes are passed in.

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