//Data array of size 3
var dataArray = ['one', 'two', 'three'];
var updateDivSelection = d3.selectAll('div').data(dataArray);
console.log(updateDivSelection[0].slice()); // [div, div, div]
updateDivSelection.html(function(d){return d;});
//enter should be empty
console.log(updateDivSelection.enter()[0].slice()); // []
//exit should be empty
console.log(updateDivSelection.exit()[0].slice()); // []
<!-- 3 div elements --> <div></div> <div></div> <div></div>