Find the smallest set of words

tough_one.js

const text = 'the dog is very large and very slow but it is my dog'.split(' ');
let smallest = [];
let smallest_array = [];
let query = {
	dog: -1,
	very: -1,
	slow: -1
}
let words_not_found = Object.keys(query);

let checkSmallest = (query) => {
	let array_of_query = Object.keys(query).map(function(v) { return query[v]; });
	if (getRange(smallest) > getRange(array_of_query)) {
		smallest_array.length = 0;
		smallest = array_of_query;
		smallest_array.push(smallest);
	} else if (getRange(smallest) === getRange(array_of_query)) {
		smallest_array.push(array_of_query)
	}
}

let getRange = (indices) => {
	let max = Math.max.apply(null, indices)
	let min = Math.min.apply(null, indices)

	return Math.abs(max - min);
}

text.forEach( (word, index) => {
	if (query[word] !== undefined) {
		query[word] = index;
		if (words_not_found.length > 0) {
			let word_found = words_not_found.indexOf(word);
			if ( word_found > -1 ) {
				words_not_found.splice(word_found, 1);
			}
		} else {
        	checkSmallest(query);
        }
	}
});

console.log(smallest);
console.log(smallest_array);