nl_tokens: The allocation of the changed nodes .
pl_tokens: function reduceChildListMutation ( mutationContent , record ) { const isAdded = Boolean ( record . addedNodes . length ) ; const isNext = Boolean ( record . nextSibling ) ; const isPrev = Boolean ( record . previousSibling ) ; const isRemoved = Boolean ( record . removedNodes . length ) ; // innerHTML or replace if ( isAdded && ( isRemoved || ( ! isRemoved && ! isNext && ! isPrev ) ) ) { while ( mutationContent . firstChild ) { mutationContent . removeChild ( mutationContent . firstChild ) ; } forEach ( record . addedNodes , function ( node ) { mutationContent . appendChild ( node ) ; } ) ; // appendChild } else if ( isAdded && ! isRemoved && ! isNext && isPrev ) { forEach ( record . addedNodes , function ( node ) { mutationContent . appendChild ( <mask> ) ; } ) ; // insertBefore } else if ( isAdded && ! isRemoved && isNext && ! isPrev ) { forEach ( record . addedNodes , function ( node ) { mutationContent . insertBefore ( node , mutationContent . firstChild ) ; } ) ; } return mutationContent ; }