Simple binary search

gistfile1.txt

/* eslint-disable */
class VelocityChecker {
	arrayData = []
	iterationsCount = 0
	from
	to

	constructor(from, to) {
		this.from = from
		this.to = to
		this.fillArrayData()
	}

	/**
	 * @param {number[]} targets
	 */
	runTestArray(targets) {
		targets.map(target => this.runTest(target))
	}

	/**
	 * @private
	 */
	reset() {
		this.iterationsCount = 0
	}

	runTest(value) {
		this.reset()

		console.log(`>>> Looking for ${value}`)
		this.targetValue = value

		this.findOneSilly(this.targetValue)
		this.findOneBinary(this.targetValue)
	}

	/**
	 * @private
	 */
	fillArrayData() {
		console.time('fillArrayData')
		for(let i = this.from; i <= this.to; i++) {
			this.arrayData.push(i)
		}

		console.timeEnd('fillArrayData')
	}

	/**
	 * @private
	 */
	findOneSilly(val) {
		console.time('findOneSilly')
		this.arrayData.indexOf(val)
		console.timeEnd('findOneSilly')
	}

	/**
	 * @private
	 */
	findOneBinary(val) {
		console.time('findOneBinary')
		const index = this.binarySearch(val, 0, this.arrayData.length - 1)
		console.timeEnd('findOneBinary')

		if(index !== null) {
			console.log(`iterations: ${this.iterationsCount} found at index ${index}`)
			return index
		}

		console.error(`Not found after ${this.iterationsCount} iterations`)
	}

	/**
	 * @private
	 * @param {number} targetValue
	 * @param {number} startIndex
	 * @param {number} endIndex
	 * @return {number|*|null}
	 */
	binarySearch(targetValue, startIndex, endIndex) {
		this.iterationsCount++
		const middle = Math.floor((startIndex + endIndex) / 2)
		// console.log(`looking for ${targetValue}`, `from ${startIndex} -`, endIndex, `with middle at ${middle}`)

		if(startIndex > endIndex) {
			return null
		}

		if(this.arrayData[middle] === targetValue) {
			return middle
		}

		return this.arrayData[middle] > targetValue
			? this.binarySearch(targetValue, startIndex, middle - 1)
			: this.binarySearch(targetValue, middle + 1, endIndex)
	}
}

const testSet = {
	range: { min: 0, max: 1e+8 },
	targets: [ -1, 0, 5e+7, 1e+8, 1e+8 + 1 ],
}

const instance = new VelocityChecker(testSet.range.min, testSet.range.max)

instance.runTestArray(testSet.targets)