warnOnce package in Refine source code.
In this article, we will review a package named warn-once. You will learn
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What is warn-once?
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Warn once usage in Refine source code
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warn-once code review
What is warn-once?
Print a warning exactly once during development. Suitable for deprecation warnings, warnings for missing setup etc.
Installation
Run the below command in your CLI to install this package
npm install warn-onceUsage
warn-once accepts 2 parameters, one is the condition and the other one is the message that gets printed to the CLI exactly once. warn-once has some underlying checks to ensure this logs only once in the CLI.
const warnOnce = require('warn-once');
// ...
warnOnce(someCondition, 'This is a warning message');Note: This warning is only shown only when NODE_ENV is not set to “production”
Warn once usage in Refine source code
So I found this package in the Refine codebase in a file named hooks/breadcrumbs/index.ts
if (action && action !== "list") {
const key = `actions.${action}`;
const actionLabel = translate(key);
if (typeof i18nProvider !== "undefined" && actionLabel === key) {
warnOnce(
true,
`[useBreadcrumb]: Breadcrumb missing translate key for the "${action}" action. Please add "actions.${action}" key to your translation file.\nFor more information, see https://refine.dev/docs/api-reference/core/hooks/useBreadcrumb/#i18n-support`,
);
breadcrumbs.push({
label: translate(
`buttons.${action}`,
textTransformers.humanize(action),
),
});
} else {
breadcrumbs.push({
label: translate(key, textTransformers.humanize(action)),
});
}
}
As you can see there are other files too, where this warn-once is used but with different parameters.
warn-once code review
index.js in the warn-once repository contains the below code
const DEV = process.env.NODE_ENV !== "production";
const warnings = new Set();
function warnOnce(condition, ...rest) {
if (DEV && condition) {
const key = rest.join(" ");
if (warnings.has(key)) {
return;
}
warnings.add(key);
console.warn(...rest);
}
}
module.exports = warnOnce;I also happened to create a Pull request with an example demonstrating the ability to pass n number of message strings as parameters.
Set is used and has check ensures the message gets logged only once.
About me:
Hey, my name is Ramu Narasinga. I study large open-source projects and create content about their codebase architecture and best practices, sharing it through articles, videos.
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