Get a diff of two json objects

json-diff.js

const diff = (a, b, path = '') => {
    let diffs = []
    const {
        type: typeA,
        value: valueA
    } = diff.meta(a)
    const {
        type: typeB,
        value: valueB
    } = diff.meta(b)
    if (typeA !== typeB) {
        diffs.push(`${path}: t{${typeA}, ${typeB}}`)
    } else if (typeA === 'array') {
        const length = Math.max(a.length, b.length)
        for (let i = 0; i < length; i++) {
            const subpath = path ? `${path}.${i}` : `${i}`
            const subDiffs = diff(a[i], b[i], subpath)
            diffs = diffs.concat(subDiffs)
        }
    } else if (typeA === 'object') {
        const keys = [...new Set([...Object.keys(a), ...Object.keys(b)])]
        for (const key of keys) {
            const subpath = path ? `${path}.${key}` : `${key}`
            const subDiffs = diff(a[key], b[key], subpath)
            diffs = diffs.concat(subDiffs)
        }
    } else if (a !== b) {
        diffs.push(`${path}: v{${valueA}, ${valueB}}`)
    }
    return diffs
}
diff.meta = o => {
    const type = diff.type(o)
    switch (type) {
        case 'date':
            return {
                type, value: o.toLocaleString()
            }
        case 'regex':
            return {
                type, value: JSON.stringify(o)
            }
        case 'error':
            return {
                type, value: o.message
            }
        case 'function':
            return {
                type, value: o.toString()
            }
        default:
            return {
                type, value: '' + o
            }
    }
}
diff.basicTypes = [
    'string',
    'number',
    'boolean',
    'function',
    'undefined',
    'null'
]
diff.type = o => {
    const type = typeof o
    if (diff.basicTypes.includes(type)) return type
    if (Array.isArray(o)) return 'array'
    if (o instanceof Date) return 'date'
    if (o instanceof RegExp) return 'regex'
    if (o instanceof Error) return 'error'
    if (o && typeof o.constructor === 'function') {
        if (o.constructor.name === 'Object') return 'object'
        return o.constructor.name
    }
    return `unknown ${type}`
}