flexbox-detecton.ja

 var testFlexBox = function textFlexBox() {

     var flexElement = document.createElement('detect');

     if (!Object.is(flexElement.style.webkitFlexWrap, 'undefined') ||
         !Object.is(flexElement.style.msFlexWrap, 'undefined') ||
         !Object.is(flexElement.style.flexWrap, 'undefined')
     ) {
         return true;
     }

 };