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;
// 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.