yoastseo-dep/src/scoring/helpers/assessments/recommendedKeywordCount.js

Yoast clientside page analysis

import getAllWordsFromTree from "../../../languageProcessing/helpers/word/getAllWordsFromTree";
import keyphraseLengthFactor from "./keyphraseLengthFactor.js";

/**
 * Calculates a recommended keyphrase count for a paper's text. The formula to calculate this number is based on the
 * keyphrase density formula.
 *
 * @param {Paper}	paper						The paper to analyze.
 * @param {number}	keyphraseLength				The length of the focus keyphrase in words.
 * @param {number}	recommendedKeyphraseDensity	The recommended keyphrase density (either maximum or minimum).
 * @param {string}	maxOrMin					Whether it's a maximum or minimum recommended keyphrase density.
 * @param {function} customGetWords				A helper to get words from the text for languages that don't use the default approach.
 *
 * @returns {number} The recommended keyphrase count.
 */
export default function( paper, keyphraseLength, recommendedKeyphraseDensity, maxOrMin, customGetWords ) {
	const wordCount = customGetWords ? customGetWords( paper.getText() ).length : getAllWordsFromTree( paper ).length;

	if ( wordCount === 0 ) {
		return 0;
	}

	const lengthKeyphraseFactor = keyphraseLengthFactor( keyphraseLength );
	const recommendedKeyphraseCount = ( recommendedKeyphraseDensity * wordCount ) / ( 100 * lengthKeyphraseFactor );

	/*
	 * The recommended keyphrase count should always be at least 2,
	 * regardless of the keyphrase density, the word count, or the keyphrase length.
	 */
	if ( recommendedKeyphraseCount < 2 ) {
		return 2;
	}

	switch ( maxOrMin ) {
		case "min":
			// Round up for the recommended minimum count.
			return Math.ceil( recommendedKeyphraseCount );
		default:
		case "max":
			// Round down for the recommended maximum count.
			return Math.floor( recommendedKeyphraseCount );
	}
}