If you do something like this in a browser or node:
var x = {};
x.case = 'things';
It will work.
However in many versions of internet explorer, it will error, with Unexpected identifier
which is obviously because you used a reserved keyword.
ieify is a module that takes perfectly valid code, and makes it even more valider for syntactically challenged environments such as internet explorer.
npm install ieify
var ieify = require('ieify');
var someCode = "var x = {class:'foo'}; x.switch = 'bar';"
ieify(someCode)
// -> var x = {"class":'foo'}; x["switch"] = 'bar';