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JS - parsing data with random single quotes

How do I parse an array of objects if it contains single quote characters?
For example, I have:
$example = '{"response":[{"uid":3202935,"first_name":"Martha","last_name":"O'Nill","user_id":3202935},{"uid":4070530,"first_name":"Alex","last_name":"White","user_id":4070530}]}';
The single quotes seem to break up the array, making parsing impossible.

You can use backticks (``). It will generate the string as it was written, with double "" and single ' quotes.
var str = `{"response":[{"uid":3202935,"first_name":"Martha","last_name":"O'Nill","user_id":3202935},{"uid":4070530,"first_name":"Alex","last_name":"White","user_id":4070530}]}`;
console.log(str);
var obj = JSON.parse(str);
console.log(obj.response[0].uid);

It's a json string not an object.
Use JSON.parse(myJsonSting) and you will get objects with the ' taken care of.

Javascript is supposed to ignore single quotes if it is inside double quotes, in your case try adding backslash before the single quote.

To parse at json string to object
var example = '{"response":[{"uid":3202935,"first_name":"Martha","last_name":"O'Nill","user_id":3202935},{"uid":4070530,"first_name":"Alex","last_name":"White","user_id":4070530}]}';
var objExample = JSON.parse(example);
To convert json object to json string
var StrExample = JSON.stringify(objExample);

Parsing string as JSON with single quotes?

I have a string
str = "{'a':1}";
JSON.parse(str);
VM514:1 Uncaught SyntaxError: Unexpected token '(…)
How can I parse the above string (str) into a JSON object ?
This seems like a simple parsing. It's not working though.

The JSON standard requires double quotes and will not accept single quotes, nor will the parser.
If you have a simple case with no escaped single quotes in your strings (which would normally be impossible, but this isn't JSON), you can simple str.replace(/'/g, '"') and you should end up with valid JSON.

I know it's an old post, but you can use JSON5 for this purpose.
<script src="json5.js"></script>
<script>JSON.stringify(JSON5.parse('{a:1}'))</script>

If you are sure your JSON is safely under your control (not user input) then you can simply evaluate the JSON. Eval accepts all quote types as well as unquoted property names.
var str = "{'a':1}";
var myObject = (0, eval)('(' + str + ')');
The extra parentheses are required due to how the eval parser works.
Eval is not evil when it is used on data you have control over.
For more on the difference between JSON.parse and eval() see JSON.parse vs. eval()

Using single quotes for keys are not allowed in JSON. You need to use double quotes.
For your use-case perhaps this would be the easiest solution:
str = '{"a":1}';
Source:
If a property requires quotes, double quotes must be used. All
property names must be surrounded by double quotes.

var str = "{'a':1}";
str = str.replace(/'/g, '"')
obj = JSON.parse(str);
console.log(obj);
This solved the problem for me.

Something like this:
var div = document.getElementById("result");
var str = "{'a':1}";
str = str.replace(/\'/g, '"');
var parsed = JSON.parse(str);
console.log(parsed);
div.innerText = parsed.a;
<div id="result"></div>

// regex uses look-forwards and look-behinds to select only single-quotes that should be selected
const regex = /('(?=(,\s*')))|('(?=:))|((?<=([:,]\s*))')|((?<={)')|('(?=}))/g;
str = str.replace(regex, '"');
str = JSON.parse(str);
The other answers simply do not work in enough cases. Such as the above cited case: "title": "Mama's Friend", it naively will convert the apostrophe unless you use regex. JSON5 will want the removal of single quotes, introducing a similar problem.
Warning: although I believe this is compatible with all situations that will reasonably come up, and works much more often than other answers, it can still break in theory.

sometimes you just get python data, it looks a little bit like json but it is not. If you know that it is pure python data, then you can eval these data with python and convert it to json like this:
echo "{'a':1}" | /usr/bin/python3 -c "import json;print(json.dumps(eval(input())))"
Output:
{"a": 1}
this is good json.
if you are in javascript, then you could use JSON.stringify like this:
data = {'id': 74,'parentId': null};
console.log(JSON.stringify(data));
Output:
> '{"id":74,"parentId":null}'

If you assume that the single-quoted values are going to be displayed, then instead of this:
str = str.replace(/\'/g, '"');
you can keep your display of the single-quote by using this:
str = str.replace(/\'/g, '\'\');
which is the HTML equivalent of the single quote.

json = ( new Function("return " + jsonString) )();

How to make string campatible for JSON.parse()

In my application when I enter value as my"name in text field the framework makes a String like (this i can not control):
"[{\"id\":\"201500000001002\",\"name\":\"my\"name\",\"colorCode\":\"\",\"version\":\"11\",\"nodeOrder\":\"1\"}]"
Now this String is passed to JSON.parse() method which produces an error because of ambiguous name field as
\"name\":\"my\"name\"
var str = JSON.parse("[{\"id\":\"201500000001002\",\"name\":\"my\"name\",\"colorCode\":\"\",\"version\":\"11\",\"nodeOrder\":\"1\"}]")
This results in JSON exception
Is there anything I can do with the string:
"[{\"id\":\"201500000001002\",\"name\":\"my\"name\",\"colorCode\":\"\",\"version\":\"11\",\"nodeOrder\":\"1\"}]"
To escape double quote character in my " name as my \" name to make it valid for JSON.parse method.
I can not control JSON String, I am just passing name as my"name and framework creates a String which is passed to JSON.parse()

I went through a series of text replace. You can try this:
var str = "[{\"id\":\"201500000001002\",\"name\":\"my\"name\",\"colorCode\":\"\",\"version\":\"11\",\"nodeOrder\":\"1\"}]";
JSON.parse(
str.replace(/\\/i,"").
replace(/{"/g,"{'").
replace(/":"/g,"':'").
replace(/","/g,"','").
replace(/"}/g,"'}").
replace(/'/g,"\###").
replace(/"/g,"\\\"").
replace(/###/g,"\"")
);
It will give back your desired JSON array

var str = "[{\"id\":\"201500000001002\"}]";
str.replace("\"*","\\\"");
var obj = JSON.parse(str);

Why is stringified JSON a valid string?

We're already aware that we cannot add double quotes inside the double quotes:
var str = ""hello""; //this will be invalid string
but when I stringify an object like this
var obj = {"name":"abc"}
var str = JSON.stringify(obj).
str // returns "{"name":"abc"}"
which is valid but shouldn't be. I'm confused as in do JavaScript have some special cases when we stringify a JSON object and omit the string validations on it?
Thanks in advance.

You can have as many double quotes inside a string literal as you want. You just need to scape them using a backslash prefix (\" instead of ").
Try this example in your browser console:
var myStr = "\"Hello\"";
myStr
You should see ""Hello"" in your console. That would be how the stringify creates a string with double quotes in it.

Replace single backslash "\" with double backslashes "\\"

I have string with file path. I want to replace all single backslashes ("\") with double backslashes ("\\").
var replaceableString = "c:\asd\flkj\klsd\ffjkl";
var part = /#"\\"/g;
var filePath = replaceableString .replace(part, /#"\\"/);
console.log(filePath);
Console showed me it.
c:asdlkjklsdfjkl
I found something like this, unfortunately it didn't work.
Replacing \ with \\

Try:
var parts = replaceableString.split('\\');
var output = parts.join('\\\\');
Personally, as I am not so expert in reg exps, I tend to avoid them when dealing with non-alphanumeric characters, both due to readability and to avoid weird mistake.

var replaceableString = "c:\asd\flkj\klsd\ffjkl";
alert(replaceableString);
This will alert you c:asdlkjklsdfjkl because '\' is an escape character which will not be considered.
To have a backslash in your string , you should do something like this..
var replaceableString = "c:\\asd\\flkj\\klsd\\ffjkl";
alert(replaceableString);
This will alert you c:\asd\flkj\klsd\ffjkl
JS Fiddle
Learn about Escape sequences here
If you want your string to have '\' by default , you should escape it .. Use escape() function
var replaceableString = escape("c:\asd\flkj\klsd\ffjkl");
alert(replaceableString);
JS Fiddle

You have several problems in your code.
To get a \ in your string variable you need to escape it.
When you create a string like this: replaceableString = "c:\asd\flkj\klsd\ffjkl"; characters with a \ before are treated as escape sequences. So during the string creation, it tries to interpret the escape sequence \a, since this is not valid it stores the a to the string. E.g. \n would have been interpreted as newline.
I assume the # is coming from a .net example. Javascript does not know "raw" strings.
remove the quotes from your regex.
This would do what you want:
var string = "c:\\asd\\flkj\\klsd\\ffjkl";
var regex = /\\/g;
var FilePath = string.replace(regex, "\\\\");

Here is the answer:
For replacing single backslash with single forward slash:
var stringReplaced = String.raw`c:\asd\flkj\klsd\ffjkl`.split('\\').join('/')
console.log(stringReplaced);
For replacing double backslash with single forward slash:
var stringReplaced = String.raw`c:\\asd\\flkj\\klsd\\ffjkl`.split('\\\\').join('/')
console.log(stringReplaced);

\ is a escape character. Therefore replaceableString does not contain any backslashes.
To fix this you should declare the string like this:
var replaceableString = "c:\\asd\\flkj\\klsd\\ffjkl";

First encode the string
then replace all occurrences of %5C with %5C%5C
At the end decode the string
var result = encodeURI(input);
result=decodeURI(result.replace(/%5C/g,"%5C%5C"));

If you have no control over the contents of the string you are trying to find backslashes in, and it contains SINGLE \ values (eg. variable myPath contains C:\Some\Folder\file.jpg), then you can actually reference the single backslashes in JavaScript as String.fromCharCode(92).
So to get the file name in my filepath example above.
var justTheName = myPath.split(String.fromCharCode(92)).pop();

In case of string matching, it is better to use encodeURIComponent, decodeURIComponent.
match(encodeURIComponent(inputString));
function match(input)
{
for(i=0; i<arr.length; i++)
{
if(arr[i] == decodeURIComponent(input))
return true;
else return false;
}
}

In the case of a single back slash in the string, the javascript replace method did not allow me to replace the single back slash.
Instead I had to use the split method which returns an array of the split strings and then concatenate the strings without the back slash (or whatever you want to replace it with)
Solution (replaced backslash with underscore):
var splitText = stringWithBackslash.split('\\');
var updatedText = splitText[0] + '_' + splitText[1];

You need to pass to pass value of a string through String.raw before you assign value to a variable.
var replaceableString = String.raw`c:\asd\flkj\klsd\ffjkl`.replace(/\\/g,"\\\\");
console.log(replaceableString)