split_by_word.js

var tweet = "These 5 incredible stories from the IDF are sure to leave #inspired";

// turn tweet into an array
var words = tweet.split(" ");

// get half the length of the words
var half_length = Math.ceil(arrayName.length / 2);

// get the words on the left side
var leftSide = words.splice(0, half_length);
var leftWords = leftSide.join(" ");

// get the words on the right side
var rightWords = words.join(" ");