warning

Print warning message in the development environment. In production environment, do nothing. This module use process.env.NODE_ENV to distinguish environments, so your build tool needs to support process.env.NODE_ENV environment variable.

API

warning(condition, message[, options])
warning.once(condition, message[, options])
warning.deprecated(condition, message[, options])

condition: Warning condition. Print message only when this parameter is true.
message: A formatted string that supports variables, such as "This is a message contains {variable}".
options: Options object.
- options.label: Warning message label. Default is "Warning". warning.deprecated's label is "Deprecated".
- options.scope: scope is next to the label and wrapped in parentheses. For example, scope: "Scope", the message is started with "Warning(Scope): ".
- options.printer: Print function. Default is console.error.
- options.variables: An object contains variables in message. ie. { variable: "value" }.
- options.deduplicated: When this option is true, a same message will be printed only once. It is true by default when using warning.once and warning.deprecated.
- options.warnedMessages: An object that saves printed messages. ie. { "Already printed message": true }.

Example

import { warning } from "@lilib/utils";

warning(
  true,
  "More than {count} {eventName} events are listened to, which may lead to memory leaks.",
  {
    scope: "EventEmitter",
    variables: {
      count: 100,
      eventName: "click",
    },
  }
);
// => "Warning(EventEmitter): More than 100 click events are listened to, which may lead to memory leaks."

API​

Example​

API

Example