# Jevlish: A JavaScript front end for Jev

> Source: <https://jacobgoldfarb.github.io/Jevlish/>
> Published: 2026-09-22 21:40:53+00:00

# Introduction

jevlish brings [Jev](https://docs.typesafe.ai) judgments into ordinary TypeScript business logic. Use `given` to judge one value and `from` to filter or rank a collection.

## What it solves

[Section titled “What it solves”](#what-it-solves)

The official Jev SDK is shaped like an LLM SDK: build a request, send it, and read the response. That is useful when the response goes to a person. In application logic, the response usually decides what code does with a value it already has—whether a ticket escalates, which rows a query keeps, or who gets assigned.

jevlish expresses those operations as conditions, filters, rankings, and choices. Exact checks remain TypeScript functions. Semantic checks remain plain-language Jev questions.

## How it works

[Section titled “How it works”](#how-it-works)

1. `given` ,`from` , and the question builders create a lazy expression. Building it sends nothing.
2. `.plan()` shows the state and questions that would leave the process.
3. `await` or`.run()` folds code predicates, compiles the remaining Noul, Score, and Choice questions, and asks Jev.
4. The acceptance policy turns model probabilities and confidences into `decided` or`uncertain` judgments.
5. The result retains the requests, answers, local predicate outcomes, usage, cache status, and policy as evidence.

## One decision

[Section titled “One decision”](#one-decision)

`means(...)` defines a reusable Noul question with an explicit boundary. `given(ticket)` supplies the subject. `.seenAs(...)` controls what leaves the process; predicates and handlers still receive the complete `Ticket`.

The branch has three outcomes. `do` handles true, `otherwise` handles false, and `whenUncertain` handles an answer that did not meet the policy. A false code predicate under `and` settles the condition locally, so a closed ticket sends no request.

## Jev vocabulary

[Section titled “Jev vocabulary”](#jev-vocabulary)

- A string condition or `means(...)` compiles to a Jev**Noul** question.
- A `scale` compiles to a**Score** question.
- `chooseFrom` compiles to a**Choice** question and maps the answer back to one of your objects.
- `ask` sends related Noul, Score, and Choice questions about one subject together.
- A **Sense** is a configured set of`given` ,`from` , and`grade` verbs bound to one runtime.

Jevlish uses the TypeSafe/Jev SDK. That is why the environment variable is `TYPESAFE_API_KEY` and the default transport is `TypeSafeClient`.

## Where to go next

[Section titled “Where to go next”](#where-to-go-next)

- [Install and configure](https://jacobgoldfarb.github.io/Jevlish/start/install/) gets a key into the process and explains the shared Sense.
- [Quickstart](https://jacobgoldfarb.github.io/Jevlish/start/quickstart/) builds one decision and one ranked query line by line.
- [Support desk](https://jacobgoldfarb.github.io/Jevlish/examples/support-desk/) runs the same domain as a complete pipeline.
- The guides cover each verb in turn, starting with [Judging one thing](https://jacobgoldfarb.github.io/Jevlish/guides/given/) .
- The [Reference](https://jacobgoldfarb.github.io/Jevlish/reference/) is generated from the root package entry point. Advanced subpath APIs are introduced in the[Runtime](https://jacobgoldfarb.github.io/Jevlish/guides/runtime/) ,[Testing](https://jacobgoldfarb.github.io/Jevlish/guides/testing/) , and[Running](https://jacobgoldfarb.github.io/Jevlish/guides/running/) guides.