constant.js 1.72 KB
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'use strict';

Object.defineProperty(exports, "__esModule", {
    value: true
});

exports.default = function () /*...values*/{
    var values = (0, _slice2.default)(arguments);
    var args = [null].concat(values);
    return function () /*...ignoredArgs, callback*/{
        var callback = arguments[arguments.length - 1];
        return callback.apply(this, args);
    };
};

var _slice = require('./internal/slice');

var _slice2 = _interopRequireDefault(_slice);

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

;

/**
 * Returns a function that when called, calls-back with the values provided.
 * Useful as the first function in a [`waterfall`]{@link module:ControlFlow.waterfall}, or for plugging values in to
 * [`auto`]{@link module:ControlFlow.auto}.
 *
 * @name constant
 * @static
 * @memberOf module:Utils
 * @method
 * @category Util
 * @param {...*} arguments... - Any number of arguments to automatically invoke
 * callback with.
 * @returns {AsyncFunction} Returns a function that when invoked, automatically
 * invokes the callback with the previous given arguments.
 * @example
 *
 * async.waterfall([
 *     async.constant(42),
 *     function (value, next) {
 *         // value === 42
 *     },
 *     //...
 * ], callback);
 *
 * async.waterfall([
 *     async.constant(filename, "utf8"),
 *     fs.readFile,
 *     function (fileData, next) {
 *         //...
 *     }
 *     //...
 * ], callback);
 *
 * async.auto({
 *     hostname: async.constant("https://server.net/"),
 *     port: findFreePort,
 *     launchServer: ["hostname", "port", function (options, cb) {
 *         startServer(options, cb);
 *     }],
 *     //...
 * }, callback);
 */
module.exports = exports['default'];