dale-chall-formula
Formula to detect the grade level of text according to the (revised) Dale–Chall readability formula.
See dale-chall for a list of words which count as “familiar”.
Install
This package is ESM only: Node 12+ is needed to use it and it must be imported
instead of required.
npm:
npm install dale-chall-formulaUse
import {daleChallFormula, daleChallGradeLevel} from 'dale-chall-formula'
daleChallFormula({word: 30, sentence: 2, difficultWord: 6}) // => 4.41208
daleChallFormula({word: 30, sentence: 2}) // => 0.744
daleChallFormula() // => NaN
daleChallGradeLevel(daleChallFormula(30, 2, 6)) // => [9, 10]API
This package exports the following identifiers: daleChallFormula,
daleChallGradeLevel.
There is no default export.
daleChallFormula(counts)
Given the number of words (word), the number of sentences (sentence), and
the number of unique unfamiliar words in a document (difficultWord), returns
the score associated with the document.
daleChallGradeLevel(score)
Given a score, returns the corresponding grade ranges
| Score | Corresponding Grade Level | Return value |
|---|---|---|
| Less than 5 | Grade 4 and lower | [0, 4] |
| Less than 6 | Grades 5 and 6 | [5, 6] |
| Less than 7 | Grades 7 and 8 | [7, 8] |
| Less than 8 | Grades 9 and 10 | [9, 10] |
| Less than 9 | Grades 11 and 12 | [11, 12] |
| Less than 10 | Grades 13 and 15 (College) | [13, 15] |
| Higher | Grades 16 and higher (College Graduate) | [16, Infinity] |
Related
automated-readability— Uses character count instead of error-prone syllable parsercoleman-liau— Uses letter count instead of an error-prone syllable parserflesch— Uses syllable countflesch-kincaid— Likeflesch-formula, returns U.S. grade levelsgunning-fog— Uses syllable count, needs POS-tagging and NERsmog-formula— Likegunning-fog-index, without needing advanced NLPspache-formula— Uses a dictionary, suited for lower reading levels