{"id":14940,"library":"sticky-module","title":"Sticky Module Singleton Utility","description":"sticky-module is a specialized JavaScript utility designed to guarantee that a given module is instantiated and evaluated only once, even across multiple imports or different bundling contexts within an application. It achieves this by storing and retrieving module instances using a unique, Symbol-based key, effectively creating an application-wide singleton for that module. This mechanism is particularly useful for libraries or components that require strict single-instance behavior to maintain consistent state or prevent redundant setup in complex module graphs, micro-frontends, or scenarios with multiple bundler outputs. The current stable version is 0.1.1. Its release cadence is likely slow, focusing on stability given its niche purpose. A key differentiator is its Symbol-based internal storage, which offers a robust and collision-resistant approach to global module caching compared to string-based keys.","status":"active","version":"0.1.1","language":"javascript","source_language":"en","source_url":"https://github.com/WebReflection/sticky-module","tags":["javascript","sticky","module"],"install":[{"cmd":"npm install sticky-module","lang":"bash","label":"npm"},{"cmd":"yarn add sticky-module","lang":"bash","label":"yarn"},{"cmd":"pnpm add sticky-module","lang":"bash","label":"pnpm"}],"dependencies":[],"imports":[{"note":"sticky-module is an ESM-first package and exposes a default export. CommonJS require() will likely fail or return an unexpected object.","wrong":"const stickyModule = require('sticky-module');","symbol":"stickyModule","correct":"import stickyModule from 'sticky-module';"},{"note":"The function returns a two-element array: the stored module object and a boolean indicating if it was already known. Destructure accordingly.","wrong":"let { config, known } = stickyModule('my-config', { config: {} });","symbol":"Module interface","correct":"let [{ config }, known] = stickyModule('my-config', { config: {} });"}],"quickstart":{"code":"import stickyModule from 'sticky-module';\n\nconsole.log('--- First attempt to get module ---');\nlet [{a, b}, known] = stickyModule('@custom/my-singleton', {\n  a: Math.random(),\n  b: 'initial value'\n});\n\nconsole.log(`Was module known? ${known}`);    // Expected: false\nconsole.log(`Module values: a=${a}, b='${b}'`); // Shows initial random 'a' and 'b'\n\n// Simulate a delay or another part of the application importing it later\nsetTimeout(() => {\n  console.log('\\n--- Second attempt to get module (after delay) ---');\n  let [{a: a2, b: b2}, known2] = stickyModule('@custom/my-singleton', {\n    a: Math.random(), // This value will be ignored as module is already stored\n    b: 'new value, ignored' // This value will also be ignored\n  });\n\n  console.log(`Was module known? ${known2}`);    // Expected: true\n  console.log(`Module values: a=${a2}, b='${b2}'`); // Shows the *same* initial random 'a' and 'b'\n\n  // Verify they are the same instance/values\n  console.log(`Are 'a' and 'a2' the same? ${a === a2}`); // Expected: true\n  console.log(`Are 'b' and 'b2' the same? ${b === b2}`); // Expected: true\n}, 100);\n","lang":"javascript","description":"Demonstrates how sticky-module ensures a module is initialized only once, returning the original instance on subsequent calls."},"warnings":[{"fix":"Be mindful of what data you store in 'sticky' modules. Ensure large objects are managed appropriately or consider if this pattern is suitable for your use case if memory pressure is a concern.","message":"The package description explicitly calls itself a 'leaky utility'. This implies that once a module is stored, it will persist in memory for the lifetime of the JavaScript realm and is not automatically garbage collected unless the application explicitly manages its removal (which sticky-module itself does not provide an API for). This is intentional for its singleton purpose but can be a concern for long-running applications or if modules store large objects.","severity":"gotcha","affected_versions":">=0.1.0"},{"fix":"Do not assume global singleton behavior across distinct JavaScript realms. If cross-realm singletons are required, an alternative inter-realm communication or shared memory solution is needed.","message":"The module uses a Symbol-based key for internal storage, which makes it effective for singleton enforcement within a single JavaScript realm (e.g., a single browser window, a Node.js process). However, this mechanism does not extend across different realms like iframes, Web Workers (without SharedWorker), or separate Node.js child processes, where each would have its own independent module storage.","severity":"gotcha","affected_versions":">=0.1.0"},{"fix":"Pin to exact versions or use care when upgrading, especially when a 1.0.0 release is made available. Review release notes thoroughly for any breaking changes.","message":"Given the current version is 0.1.1, any future major release (e.g., 1.0.0) is very likely to introduce breaking changes without a deprecation cycle. APIs might change significantly, or internal mechanisms could be altered.","severity":"breaking","affected_versions":"<1.0.0"}],"env_vars":null,"search_vec":"'0.1.1':105 'achiev':38 'across':27 'applic':36,57 'application-wid':56 'approach':137 'base':51,126,146 'behavior':78 'bundl':32 'bundler':98 'cach':141 'cadenc':108 'collis':135 'collision-resist':134 'compar':142 'complex':88 'compon':71 'consist':81 'context':33 'creat':54 'current':101 'design':13 'differ':31 'differenti':121 'effect':53 'evalu':23 'even':26 'focus':112 'frontend':93 'given':18,115 'global':139 'graph':90 'guarante':15 'import':29 'instanc':45,77 'instanti':21 'intern':127 'javascript':11,148 'key':52,120,147 'librari':69 'like':110 'maintain':80 'mechan':64 'micro':92 'micro-frontend':91 'modul':2,7,19,44,62,89,140,150 'multipl':28,97 'nich':117 'offer':130 'output':99 'particular':66 'prevent':84 'purpos':118 'redund':85 'releas':107 'requir':73 'resist':136 'retriev':43 'robust':132 'scenario':95 'setup':86 'singl':76 'single-inst':75 'singleton':3,59 'slow':111 'special':10 'stabil':114 'stabl':102 'state':82 'sticki':1,6,149 'sticky-modul':5 'storag':128 'store':41 'strict':74 'string':145 'string-bas':144 'symbol':50,125 'symbol-bas':49,124 'uniqu':48 'use':46,67 'util':4,12 'version':103 'wide':58 'within':34","created_at":"2026-04-20T18:44:24.982333+00:00","updated_at":"2026-04-20T18:44:24.982333+00:00","problems":[{"fix":"Ensure you are using `import stickyModule from 'sticky-module';` in an ESM context. If using CommonJS, check your build tools for proper ESM-to-CJS interop or consider using dynamic import `import('sticky-module').then(m => m.default)`.","cause":"This typically occurs when attempting to import 'sticky-module' using CommonJS `require()` syntax in a project that expects ESM, or if transpilation is misconfigured, leading to the default export not being correctly resolved.","error":"TypeError: stickyModule is not a function"},{"fix":"Use the correct default import syntax: `import stickyModule from 'sticky-module';`. If in TypeScript, ensure `\"esModuleInterop\": true` and `\"allowSyntheticDefaultImports\": true` are set in your `tsconfig.json`.","cause":"This error can occur if you're trying to destructure a named export when `sticky-module` only provides a default export, or if your TypeScript configuration (e.g., `esModuleInterop`) is not correctly set up for handling default ESM imports.","error":"Module 'sticky-module' has no default export."}],"ecosystem":"npm","meta_description":null,"install_score":null,"quickstart_score":null,"quickstart_tag":null,"pypi_latest":null,"cli_name":"","cli_version":null,"type":"library","homepage":null,"github":"https://github.com/WebReflection/sticky-module","docs":null,"changelog":null,"pypi":null,"npm":"https://www.npmjs.com/package/sticky-module","openapi_spec":null,"status_page":null,"smithery":null,"categories":[],"base_url":null,"auth_type":null,"provenance":{"verified_status":null,"verified_at":null,"last_verified":"2026-06-17","next_check":"2026-07-18","install_tag":null}}