@tldraw/utils/src/lib/hash.ts

tldraw infinite canvas SDK (private utilities).

/**
 * Hash a string using the FNV-1a algorithm.
 *
 * @public
 */
export function getHashForString(string: string) {
	let hash = 0
	for (let i = 0; i < string.length; i++) {
		hash = (hash << 5) - hash + string.charCodeAt(i)
		hash |= 0 // Convert to 32bit integer
	}
	return hash + ''
}

/**
 * Hash a string using the FNV-1a algorithm.
 *
 * @public
 */
export function getHashForObject(obj: any) {
	return getHashForString(JSON.stringify(obj))
}

/**
 * Hash an ArrayBuffer using the FNV-1a algorithm.
 *
 * @public
 */
export function getHashForBuffer(buffer: ArrayBuffer) {
	const view = new DataView(buffer)
	let hash = 0
	for (let i = 0; i < view.byteLength; i++) {
		hash = (hash << 5) - hash + view.getUint8(i)
		hash |= 0 // Convert to 32bit integer
	}
	return hash + ''
}

/** @public */
export function lns(str: string) {
	const result = str.split('')
	result.push(...result.splice(0, Math.round(result.length / 5)))
	result.push(...result.splice(0, Math.round(result.length / 4)))
	result.push(...result.splice(0, Math.round(result.length / 3)))
	result.push(...result.splice(0, Math.round(result.length / 2)))
	return result
		.reverse()
		.map((n) => (+n ? (+n < 5 ? 5 + +n : +n > 5 ? +n - 5 : n) : n))
		.join('')
}