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# disallow template literals as report messages (prefer-placeholders)
Report messages in rules can have placeholders surrounded by curly brackets.
```js
context.report({
node,
message: '{{disallowedNode}} nodes are not allowed.',
data: { disallowedNode: node.type }
});
```
Using placeholders is often preferred over using dynamic report messages, for a few reasons:
* They can help enforce a separation of the message and the data.
* It will be easier to migrate when ESLint starts supporting placing lint messages in metadata (see [#6740](https://github.com/eslint/eslint/issues/6740))
## Rule Details
This rule aims to report string concatenation and template literals in report messages.
Examples of **incorrect** code for this rule:
```js
/* eslint eslint-plugin/prefer-placeholders: error */
module.exports = {
create(context) {
context.report({
node,
message: `The node ${node.name} is not allowed to be used.`
});
context.report({
node,
message: 'The node ' + node.name + ' is not allowed to be used.'
});
}
};
```
Examples of **correct** code for this rule:
```js
/* eslint eslint-plugin/prefer-placeholders: error */
module.exports = {
create(context) {
context.report({
node,
message: 'The node {{name}} is not allowed to be used.',
data: { name: node.name }
});
}
};
```
## When Not To Use It
If you need to use string concatenation in your report messages for some reason, don't turn on this rule.
## Further Reading
* [context.report() API](http://eslint.org/docs/developer-guide/working-with-rules#contextreport)
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