json-schema-library/src/keywords/multipleOf.ts

Customizable and hackable json-validator and json-schema utilities for traversal, data generation and validation

import { getPrecision } from "../utils/getPrecision";
import { Keyword, JsonSchemaValidatorParams } from "../Keyword";

export const multipleOfKeyword: Keyword = {
    id: "multipleOf",
    keyword: "multipleOf",
    addValidate: ({ schema }) => !isNaN(schema.multipleOf),
    validate: validateMultipleOf
};

function validateMultipleOf({ node, data, pointer }: JsonSchemaValidatorParams) {
    if (typeof data !== "number") {
        return undefined;
    }
    const { schema } = node;
    const valuePrecision = getPrecision(data);
    const multiplePrecision = getPrecision(schema.multipleOf);
    if (valuePrecision > multiplePrecision) {
        // value with higher precision then multipleOf-precision can never be multiple
        return node.createError("multiple-of-error", {
            multipleOf: schema.multipleOf,
            value: data,
            pointer,
            schema
        });
    }

    const precision = Math.pow(10, multiplePrecision);
    const val = Math.round(data * precision);
    const multiple = Math.round(schema.multipleOf * precision);
    if ((val % multiple) / precision !== 0) {
        return node.createError("multiple-of-error", {
            multipleOf: schema.multipleOf,
            value: data,
            pointer,
            schema
        });
    }

    // maybe also check overflow
    // https://stackoverflow.com/questions/1815367/catch-and-compute-overflow-during-multiplication-of-two-large-integers
    return undefined;
}