str[0]-->str.charAt(0), for ie7

[Kirk-Wang]

function capitalize(str: string, i: number): string {
if (i === 0) {
return str;
}

return str[0].toUpperCase() + str.slice(1);
}

[Bloomca]

Hey, thanks for the suggestion!

However, do we really need it? For example, react dropped support for IE8.

I am not sure about redux, but found this comment from @gaearon