Example 3-14. Conditionally expanding a chain based on the outcome of a preceding promise

function readAllChunks(readableStream) {
	var reader = readableStream.getReader();
	var chunks = [];
	
	return pump();
	
	function pump() {
		return reader.read().then(function (result) {
			if (result.done) {
				return chunks;
			}
			
			chunks.push(result.value);
			return pump();
		});
	}
}