Using a variable key in chrome.storage.local.set [duplicate]

Answer 1

I have solved the problem. Instead of using chrome.storage.local.set({key:val[key]+param1});

I have replaced the json string {key:val[key]+param1} with an object.

var obj = {};       
var key = "myKey";  
obj[key] += param1;   
chrome.storage.local.set(obj);

Here obj has value {"myKey":"the appended value"}