@extra-object/is-entry/index.js

Checks if object has an entry.

'use strict';

/**
 * Gives same value.
 * @param v a value
 * @returns v
 */
function id(v) {
    return v;
}

/**
 * Compares two values.
 * @param a a value
 * @param b another value
 * @returns a<b: -ve, a=b: 0, a>b: +ve
 */
function cmp(a, b) {
    return a < b ? -1 : (a > b ? 1 : 0);
}

/**
 * Checks if object has an entry.
 * @param x an object
 * @param e entry?
 * @param fc compare function (a, b)
 * @param fm map function (v, k, x)
 */
function isEntry(x, e, fc = null, fm = null) {
    var fc = fc || cmp, fm = fm || id, [k, v] = e;
    return x.hasOwnProperty(k) && fc(fm(x[k], k, x), v) === 0;
}

module.exports = isEntry;