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Split String using backslash in javascript

This is my Temp url and I'm trying to get image name
var str='C:\fakepath\alfa_company.png';
my expected out put like this:
var url='alfa_company.png';

In Javascript "\" has a special meaning.
So, it doesn't get included in your resultant string.
Try
let u = String.raw`C:\fakepath\alfa_company.png`;
u.split("\\")[u.split("\\").length-1]
or
let u = String.raw`C:\fakepath\alfa_company.png`;
u.split("\\").pop()
to understand it better go through How can I use backslashes (\) in a string?

You don't need any jQuery for that :)
const path = 'C:\\fakepath\\alfa_company.png';
const filename = path.split('\\').pop(); // alfa_company.png
You need to use double backlashes because JavaScript treats them as escape characters.

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);

Split between two character in javascript

this is my string,
var str=""{\"checkedRows\":\"[{\"SlNo\":\"1\",\"ItemCode\":\"8\",\"ItemDetail\":\"Cassue Nut\",\"Qty\":\"140\",\"Rate\":\"2000\",\"Amount\":280000\"}]\",\"checkedIndex\":\"[0]\"}"";
I'm trying to get substring as below
[{\"SlNo\":\"1\",\"ItemCode\":\"8\",\"ItemDetail\":\"Cassue Nut\",\"Qty\":\"140\",\"Rate\":\"2000\",\"Amount\":280000\"}]
And i'm trying below code to split
var newStr = str.substring(str.lastIndexOf("[") + 1, str.lastIndexOf("]"))
but unable to fetch it.

Firstly note that you have an extra leading and trailing double quote around your JSON string. Secondly the JSON itself is completely malformed. You need to fix the errors it has (extra/mis-matched double quotes mostly) so it looks like this:
'{"checkedRows":[{"SlNo":"1","ItemCode":"8","ItemDetail":"Cassue Nut","Qty":"140","Rate":"2000","Amount":280000}],"checkedIndex":[0]}'
Once you've done that you can parse the string to an object, then retrieve the checkedRows property and stringify that again, like this:
var str = '{"checkedRows":[{"SlNo":"1","ItemCode":"8","ItemDetail":"Cassue Nut","Qty":"140","Rate":"2000","Amount":280000}],"checkedIndex":[0]}';
var obj = JSON.parse(str);
var newStr = JSON.stringify(obj.checkedRows);
console.log(newStr);

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 Characters from string with javascript

I have a string like (which is a shared path)
\\cnyc12p20005c\mkt$\\XYZ\
I need to replace all \\ with single slash so that I can display it in textbox. Since it's a shared path the starting \\ should not be removed. All others can be removed.
How can I achieve this in JavaScript?

You could do it like this:
var newStr = str.replace(/(.)\\{2}/, "$1\\");
Or this, if you don't like having boobs in your code:
var newStr = "\\" + str.split(/\\{1,2}/).join("\\");

You can use regular expression to achieve this:
var s = '\\\\cnyc12p20005c\\mkt$\\\\XYZ\\';
console.log(s.replace(/.\\\\/g, '\\')); //will output \\cnyc12p20005c\mkt$\XYZ\
Double backslashes are used because backslash is special character and need to be escaped.