Check if a string is a valid JSON

This is useful for making sure that the JSON is valid before you perform another operation on it. You can learn more about how to use json parse on WebReference. While working, this json formatter and validator is a handy tool.

function isJson(str) {
    try {
        JSON.parse(str);
    } catch (e) {
      //the json is  not ok
        return false;
    }
    //the json is ok
    return true;									
}

Source

https://github.com/roeib/JavaScript-snippets#check-if-a-string-is-a-valid-json