JavaScript - Escape double quotes

It should be:

var str='[{"Company": "XYZ","Description": "\\"TEST\\""}]';

First, I changed the outer quotes to single quotes, so they won't conflict with the inner quotes. Then I put backslash before the innermost quotes around TEST, to escape them. And I escaped the backslash so that it will be treated literally.

You can get the same result with use of a JSON function:

var str=JSON.stringify({Company: "XYZ", Description: '"TEST"'});

Here the inner quote is escaped and the entire string is taken in single quote.

var str = '[{ "Company": "XYZ", "Description": "\\"TEST\\""}]';