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*   [Get started](/v0.1/docs/get_started/)
    
    *   [Introduction](/v0.1/docs/get_started/introduction/)
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            *   [Quick Start](/v0.1/docs/modules/model_io/output_parsers/quick_start/)
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            *   [Output Parser Types](/v0.1/docs/modules/model_io/output_parsers/types/)
                
                *   [String output parser](/v0.1/docs/modules/model_io/output_parsers/types/string/)
                *   [HTTP Response Output Parser](/v0.1/docs/modules/model_io/output_parsers/types/http_response/)
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                *   [Combining output parsers](/v0.1/docs/modules/model_io/output_parsers/types/combining_output_parser/)
                *   [List parser](/v0.1/docs/modules/model_io/output_parsers/types/csv/)
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*   [](/v0.1/)
*   [Modules](/v0.1/docs/modules/)
*   [Model I/O](/v0.1/docs/modules/model_io/)
*   [Output Parsers](/v0.1/docs/modules/model_io/output_parsers/)
*   [Output Parser Types](/v0.1/docs/modules/model_io/output_parsers/types/)
*   Custom list parser

Custom list parser
==================

This output parser can be used when you want to return a list of items with a specific length and separator.

tip

See [this section for general instructions on installing integration packages](/v0.1/docs/get_started/installation/#installing-integration-packages).

*   npm
*   Yarn
*   pnpm

    npm install @langchain/openai

    yarn add @langchain/openai

    pnpm add @langchain/openai

    import { OpenAI } from "@langchain/openai";import { PromptTemplate } from "@langchain/core/prompts";import { CustomListOutputParser } from "@langchain/core/output_parsers";import { RunnableSequence } from "@langchain/core/runnables";// With a `CustomListOutputParser`, we can parse a list with a specific length and separator.const parser = new CustomListOutputParser({ length: 3, separator: "\n" });const chain = RunnableSequence.from([  PromptTemplate.fromTemplate(    "Provide a list of {subject}.\n{format_instructions}"  ),  new OpenAI({ temperature: 0 }),  parser,]);/*Provide a list of great fiction books (book, author).Your response should be a list of 3 items separated by "\n" (eg: `foo\n bar\n baz`)*/const response = await chain.invoke({  subject: "great fiction books (book, author)",  format_instructions: parser.getFormatInstructions(),});console.log(response);/*[  'The Catcher in the Rye, J.D. Salinger',  'To Kill a Mockingbird, Harper Lee',  'The Great Gatsby, F. Scott Fitzgerald']*/

#### API Reference:

*   [OpenAI](https://api.js.langchain.com/classes/langchain_openai.OpenAI.html) from `@langchain/openai`
*   [PromptTemplate](https://api.js.langchain.com/classes/langchain_core_prompts.PromptTemplate.html) from `@langchain/core/prompts`
*   [CustomListOutputParser](https://api.js.langchain.com/classes/langchain_core_output_parsers.CustomListOutputParser.html) from `@langchain/core/output_parsers`
*   [RunnableSequence](https://api.js.langchain.com/classes/langchain_core_runnables.RunnableSequence.html) from `@langchain/core/runnables`

* * *

#### Help us out by providing feedback on this documentation page:

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