is-object.js

"use strict";

// Returns true when the value is a regular Object and not a specialized Object
//
// This helps speeding up deepEqual cyclic checks
// The premise is that only Objects are stored in the visited array.
// So if this function returns false, we don't have to do the
// expensive operation of searching for the value in the the array of already
// visited objects
function isObject(value) {
    return (
        typeof value === "object" &&
        value !== null &&
        // none of these are collection objects, so we can return false
        !(value instanceof Boolean) &&
        !(value instanceof Date) &&
        !(value instanceof Error) &&
        !(value instanceof Number) &&
        !(value instanceof RegExp) &&
        !(value instanceof String)
    );
}

module.exports = isObject;