@loopback/docs

--- lang: en title: 'API docs: openapi-spec-builder.builderbase' keywords: LoopBack 4.0, LoopBack 4, Node.js, TypeScript, OpenAPI sidebar: lb4_sidebar editurl: https://github.com/loopbackio/loopback-next/tree/master/packages/openapi-spec-builder permalink: /doc/en/lb4/apidocs.openapi-spec-builder.builderbase.html ---  [Home](./index.md) > [@loopback/openapi-spec-builder](./openapi-spec-builder.md) > [BuilderBase](./openapi-spec-builder.builderbase.md) ## BuilderBase class **Signature:** ```typescript export declare class BuilderBase<T extends ISpecificationExtension> ``` ## Constructors <table><thead><tr><th> Constructor </th><th> Modifiers </th><th> Description </th></tr></thead> <tbody><tr><td markdown="1"> [(constructor)(initialSpec)](./openapi-spec-builder.builderbase._constructor_.md) </td><td markdown="1"> </td><td markdown="1"> Constructs a new instance of the `BuilderBase` class </td></tr> </tbody></table> ## Properties <table><thead><tr><th> Property </th><th> Modifiers </th><th> Type </th><th> Description </th></tr></thead> <tbody><tr><td markdown="1"> [\_spec](./openapi-spec-builder.builderbase._spec.md) </td><td markdown="1"> `protected` </td><td markdown="1"> T </td><td markdown="1"> </td></tr> </tbody></table> ## Methods <table><thead><tr><th> Method </th><th> Modifiers </th><th> Description </th></tr></thead> <tbody><tr><td markdown="1"> [build()](./openapi-spec-builder.builderbase.build.md) </td><td markdown="1"> </td><td markdown="1"> Build the spec object. </td></tr> <tr><td markdown="1"> [withExtension(key, value)](./openapi-spec-builder.builderbase.withextension.md) </td><td markdown="1"> </td><td markdown="1"> Add a custom (extension) property to the spec object. </td></tr> </tbody></table>