# iterable-string-interceptor > Intercept iterable string - backbone for template engines Latest version **3.1.0** (published 2026-09-18) · 0BSD license · 0 weekly downloads ## Install ```sh npm install iterable-string-interceptor pnpm add iterable-string-interceptor yarn add iterable-string-interceptor bun add iterable-string-interceptor ``` ## Health **Score 65/100 (B)** — status: active. Positive: esm support; no vulnerabilities; has provenance; recently updated; high maintenance score. Warnings: low downloads; no types. ## Facts | | | |---|---| | Version | 3.1.0 | | Published | 2026-09-18 | | First published | 2018-12-31 | | Weekly downloads | 0 | | License | 0BSD | | TypeScript types | none | | Module format | ESM + CommonJS | | Node | >=24.21.0 | | Dependencies | 0 | | Unpacked size | 11 KB | | Known vulnerabilities | 0 | | Install scripts | no | | Provenance | attested (GitHub Actions) | | GitHub stars | 1 | | Maintainers | arlac77 | | Keywords | chunk, iterable, template | ## Links - npm: https://www.npmjs.com/package/iterable-string-interceptor - Repository: https://github.com/arlac77/iterable-string-interceptor - Homepage: https://github.com/arlac77/iterable-string-interceptor#readme - Issues: https://github.com/arlac77/iterable-string-interceptor/issues - npm.io page: https://npm.io/package/iterable-string-interceptor ## Recent versions - 3.1.0 (latest) — 2026-09-18 - 3.0.8 — 2026-03-12 - 3.0.7 — 2026-02-17 - 3.0.6 — 2026-01-22 - 3.0.5 — 2026-01-13 - 3.0.4 — 2026-01-13 - 3.0.3 — 2025-11-26 - 3.0.2 — 2025-05-06 - 3.0.1 — 2025-05-06 - 3.0.0 — 2024-03-08 - 2.3.1 — 2024-02-08 - 2.3.0 — 2024-02-08 - 2.2.4 — 2023-05-01 - 2.2.3 — 2022-12-30 - 2.2.2 — 2022-11-22 - … 24 more at https://npm.io/package/iterable-string-interceptor/versions ## README [![npm](https://img.shields.io/npm/v/iterable-string-interceptor.svg)](https://www.npmjs.com/package/iterable-string-interceptor) [![License](https://img.shields.io/badge/License-0BSD-blue.svg)](https://spdx.org/licenses/0BSD.html) [![Typed with TypeScript](https://flat.badgen.net/badge/icon/Typed?icon=typescript\&label\&labelColor=blue\&color=555555)](https://typescriptlang.org) [![bundlejs](https://deno.bundlejs.com/?q=iterable-string-interceptor\&badge=detailed)](https://bundlejs.com/?q=iterable-string-interceptor) [![downloads](http://img.shields.io/npm/dm/iterable-string-interceptor.svg?style=flat-square)](https://npmjs.org/package/iterable-string-interceptor) [![GitHub Issues](https://img.shields.io/github/issues/arlac77/iterable-string-interceptor.svg?style=flat-square)](https://github.com/arlac77/iterable-string-interceptor/issues) [![Build Status](https://img.shields.io/endpoint.svg?url=https%3A%2F%2Factions-badge.atrox.dev%2Farlac77%2Fiterable-string-interceptor%2Fbadge\&style=flat)](https://actions-badge.atrox.dev/arlac77/iterable-string-interceptor/goto) [![Styled with prettier](https://img.shields.io/badge/styled_with-prettier-ff69b4.svg)](https://github.com/prettier/prettier) [![Commitizen friendly](https://img.shields.io/badge/commitizen-friendly-brightgreen.svg)](http://commitizen.github.io/cz-cli/) [![Known Vulnerabilities](https://snyk.io/test/github/arlac77/iterable-string-interceptor/badge.svg)](https://snyk.io/test/github/arlac77/iterable-string-interceptor) # iterable-string-interceptor Intercept Iterable string - backbone for template engines ```javascript import { iterableStringInterceptor } from "iterable-string-interceptor"; import { createReadStream } from "fs"; import { readFile } from "fs/promises"; // double values inside {{}} // {{7}} -> 14 for await (const chunk of iterableStringInterceptor(createReadStream('aFile', { encoding: "utf8" }), expression => expression * 2 )) { process.stdout.write(chunk); } ``` ```javascript import { iterableStringInterceptor } from "iterable-string-interceptor"; import { createReadStream } from "fs"; import { readFile } from "fs/promises"; // handle expression as to be included content {{filename}} for await (const chunk of iterableStringInterceptor(createReadStream('aFile', { encoding: "utf8" }), async * (expression) => { yield readFile(expression, { encoding: "utf8" }); } )) { process.stdout.write(chunk); } ``` # API ### Table of Contents * [ExpressionTransformer](#expressiontransformer) * [Parameters](#parameters) * [EarlyConsumerCallback](#earlyconsumercallback) * [Parameters](#parameters-1) * [iterableStringInterceptor](#iterablestringinterceptor) * [Parameters](#parameters-2) ## ExpressionTransformer Type: function ([string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String), [string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String), Iterable<[string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)>, [EarlyConsumerCallback](#earlyconsumercallback), [string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String), [string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)): AsyncIterable<[string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)> ### Parameters * `expression` **[string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** detected expression without leadIn / leadOut * `remainder` **[string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** chunk after leadOut * `source` **Iterable<[string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)>** original source * `cb` **[EarlyConsumerCallback](#earlyconsumercallback)** to be called if remainder has changed * `leadIn` **[string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** expression entry sequence * `leadOut` **[string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** expression exit sequence Returns **AsyncIterable<[string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)>** transformed source ## EarlyConsumerCallback Will be called from the ExpressionTransformer if the given remainder needs to be altered. Type: function ([string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)): void ### Parameters * `remainder` **[string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** new remainder to be used by iterableStringInterceptor ## iterableStringInterceptor Intercept into a async iterable string source, detecting lead in/outs like '{{' and '}}' and asking a transformer for a replacement iterable string. ### Parameters * `source` **Iterable<[string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)>** * `transform` **[ExpressionTransformer](#expressiontransformer)** * `leadIn` **[string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** expression entry sequence (optional, default `"{{"`) * `leadOut` **[string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** expression exit sequence (optional, default `"}}"`) Returns **AsyncIterable<[string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)>** transformed source # install With [npm](http://npmjs.org) do: ```shell npm install iterable-string-interceptor ``` # license BSD-2-Clause --- _Source: https://npm.io/package/iterable-string-interceptor · Machine-readable twin of the npm.io package page. 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