Accessing individual characters in strings as if they are arrays is an ECMAScript 5 feature which was only introduced in IE8. So IE 7 and below (and IE11 when in compatibility mode) are erroring because of this.
Notably this is leaving accordions in a state where the original page content has been removed (because they use the js-hidden class), but the accordion fails to initialise, leaving the user with no way to navigate further.
We can fix this by using charAt1 as recommended by MDN 2
Accessing individual characters in strings as if they are arrays is an ECMAScript 5 feature which was only introduced in IE8. So IE 7 and below (and IE11 when in compatibility mode) are erroring because of this.
Notably this is leaving accordions in a state where the original page content has been removed (because they use the js-hidden class), but the accordion fails to initialise, leaving the user with no way to navigate further.
We can fix this by using
charAt1 as recommended by MDN 2