@reactivex/ix-es5-esm/iterable/first.js

The Interactive Extensions for JavaScript

import { __values } from "tslib";
/**
 * Returns the first element of an iterable sequence that matches the predicate if provided, or undefined if no such element exists.
 *
 * @template T The type of the elements in the source sequence.
 * @param {Iterable<T>} source Source async-enumerable sequence.
 * @returns {(S | undefined)} The first element in the iterable sequence, or undefined if no such element exists.
 */
export function first(source, options) {
    var e_1, _a;
    var _b = options || {}, thisArg = _b["thisArg"], _c = _b["predicate"], predicate = _c === void 0 ? function () { return true; } : _c;
    var i = 0;
    try {
        for (var source_1 = __values(source), source_1_1 = source_1.next(); !source_1_1.done; source_1_1 = source_1.next()) {
            var item = source_1_1.value;
            if (predicate.call(thisArg, item, i++)) {
                return item;
            }
        }
    }
    catch (e_1_1) { e_1 = { error: e_1_1 }; }
    finally {
        try {
            if (source_1_1 && !source_1_1.done && (_a = source_1.return)) _a.call(source_1);
        }
        finally { if (e_1) throw e_1.error; }
    }
    return undefined;
}

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