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simple focus-within polyfill
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(function(window, document){ | |
'use strict'; | |
var slice = [].slice; | |
var removeClass = function(elem){ | |
elem.classList.remove('focus-within'); | |
}; | |
var update = (function(){ | |
var running, last; | |
var action = function(){ | |
var element = document.activeElement; | |
running = false; | |
if(last !== element){ | |
last = element; | |
slice.call(document.getElementsByClassName('focus-within')).forEach(removeClass); | |
while(element && element.classList){ | |
element.classList.add('focus-within'); | |
element = element.parentNode; | |
} | |
} | |
}; | |
return function(){ | |
if(!running){ | |
requestAnimationFrame(action); | |
running = true; | |
} | |
}; | |
})(); | |
document.addEventListener('focus', update, true); | |
document.addEventListener('blur', update, true); | |
update(); | |
})(window, document); |
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