Question

I have a textbox that posts info to the server and it’s in JSON format. Lets say I want to enter two quotes for the value, and the JSON struct would look like:

{
    "test": """"
}

I need it to look like:

{
    "test": "\"\""
}

so it will follow JSON standards and can be parsable/stringifyable.

I tried using

 var val = myVal.replace('"', "\\\"");

but this didn’t work. val ends up with only one escaped quote like so \""Any help is much appreciated!

Answer 1

My answer makes some assumptions, as I’ve had to fill in the rather sizeable gaps in your question:

• The user will enter a text string into a textbox;
• Your script will read the textbox contents, and use those contents as the value of one of the items in a JSON string that it’s building;
• The script sends this resulting JSON string to the server somehow.

If I’ve got that right, let’s proceed…

---

Baseline code

So, with some placeholders, you’re doing:

function get_contents_of_textbox() {
   // Dummy data for example
   return 'My mum pushed and I said "Hello World"!';
}

function send_to_server(json_str) {
   // Dummy action: display JSON string
   console.log(json_str);
}

var myVal = get_contents_of_textbox();
var JSON  = '{ "test": "' + myVal + '" }';
send_to_server(JSON);

Live demo, showing the malformed JSON.

---

Initial attempt

To ensure that JSON is valid, escape any quotes and backslashes that it may contain. You already gave it a go:

myVal = myVal.replace('"', "\\\"");

and the result of your attempt is:

{ "test": "My mum pushed and I said \"Hello World"!" }

Only the first quote has been escaped. This is because only one instance of the search string is replaced by default.

The Mozilla documentation says:

To perform a global search and replace, either include the g flag in
the regular expression or if the first parameter is a string, include
g in the flags parameter.

---

Working attempt

Unfortunately, the flags parameter is non-standard, so let’s switch to the regex version of replace, and use the /g switch in it:

myVal = myVal.replace(/"/g, '\\"');

^{(You’ll notice that I also condensed the replacement string, for brevity.)}

Result:

{ "test": "My mum pushed and I said \"Hello World\"!" }

Live demo. Hurrah!

---

Complete solution

Let’s also add logic to escape backslashes, and we end up with this:

function get_contents_of_textbox() {
   // Dummy data for example
   return 'My mum pushed [a back\\slash] and I said "Hello World"!';
}

function send_to_server(json_str) {
   // Dummy action: display JSON string
   console.log(json_str);
}

var myVal = get_contents_of_textbox();
myVal = myVal.replace(/\\/g, '\\\\'); // escape backslashes
myVal = myVal.replace(/"/g, '\\"');   // escape quotes

var JSON  = '{ "test": "' + myVal + '" }';
send_to_server(JSON);

Result:

{ "test": "My mum pushed [a back\\slash] and I said \"Hello World\"!" }

Live demo.