guardz/dist/typeguards/isEqualTo.js

A simple and lightweight TypeScript type guard library for runtime type validation.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.isEqualTo = isEqualTo;
const generateTypeGuardError_1 = require("./generateTypeGuardError");
const stringify_1 = require("../stringify");
/**
 * Creates a type guard that checks if a value is exactly equal to a specific value.
 *
 * Uses strict equality (===) for comparison. This is useful for literal types
 * and specific value validation.
 *
 * @template T - The literal type of the expected value
 * @param expectedValue - The exact value to compare against
 * @returns A type guard function that validates exact equality
 *
 * @example
 * ```typescript
 * import { isEqualTo } from 'guardz';
 *
 * const isHello = isEqualTo("hello");
 * const isZero = isEqualTo(0);
 * const isTrue = isEqualTo(true);
 * const isNull = isEqualTo(null);
 *
 * console.log(isHello("hello")); // true
 * console.log(isHello("Hello")); // false (case sensitive)
 * console.log(isZero(0)); // true
 * console.log(isZero("0")); // false (different types)
 * console.log(isTrue(true)); // true
 * console.log(isTrue(1)); // false
 *
 * // Useful for literal types
 * type Theme = "light" | "dark";
 * const isLightTheme = isEqualTo("light" as const);
 *
 * const data: unknown = getUserInput();
 * if (isLightTheme(data)) {
 *   // data is now typed as "light"
 *   console.log("Light theme selected");
 * }
 * ```
 */
function isEqualTo(expectedValue) {
    return function (value, config) {
        if (value !== expectedValue) {
            if (config) {
                config.callbackOnError((0, generateTypeGuardError_1.generateTypeGuardError)(value, config.identifier, `equal to ${(0, stringify_1.stringify)(expectedValue)}`));
            }
            return false;
        }
        return true;
    };
}