Getting started

[John-L]

Node.js Version

v24.14.0

NPM Version

v11.9.0

Operating System

Win11 25H2

Subsystem

constants

Description

I'm new to Node.js. All my previous experience with JavaScript is when it is browser-hosted.

Is there a node program control that disables the variable declaration requirement, so that variables can be implicitly declared when an assignment occurs (similar to browser-hosted implementations)?

Minimal Reproduction

file="one";

vs.

const file="one"; or var file="one";

Output

file="one";
^

ReferenceError: file is not defined
at file:///C:/Users/Public/npm/Sample-Const.js:1:5
at ModuleJob.run (node:internal/modules/esm/module_job:430:25)
at async onImport.tracePromise.proto (node:internal/modules/esm/loader:661:26)
at async asyncRunEntryPointWithESMLoader (node:internal/modules/run_main:101:5)

Node.js v24.14.0

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• I have looked for issues that already exist before submitting this
• My issue follows the guidelines in the README file, and follows the 'How to ask a good question' guide at https://stackoverflow.com/help/how-to-ask

[avivkeller]

Is there a node program control that disables the variable declaration requirement, so that variables can be implicitly declared when an assignment occurs (similar to browser-hosted implementations)?

Yes. Node.js, and all JavaScript for that matter, either runs in strict or non-strict mode. When running in strict mode, variables must be explicitly declared with their keywords. In non-strict mode, this is not a requirement.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Strict_mode#invoking_strict_mode