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noTemplateCurlyInString

src/content/docs/linter/rules/no-template-curly-in-string.mdx

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import { Tabs, TabItem } from '@astrojs/starlight/components';

<Tabs> <TabItem label="JavaScript (and super languages)" icon="seti:javascript"> ## Summary - Rule available since: `v1.9.3` - Diagnostic Category: [`lint/suspicious/noTemplateCurlyInString`](/reference/diagnostics#diagnostic-category) - This rule is **recommended**, meaning it is enabled by default. - This rule doesn't have a fix. - The default severity of this rule is [**warning**](/reference/diagnostics#warning). - Sources: - Same as [`no-template-curly-in-string`](https://eslint.org/docs/latest/rules/no-template-curly-in-string)

How to configure

json
{
	"linter": {
		"rules": {
			"suspicious": {
				"noTemplateCurlyInString": "error"
			}
		}
	}
}

Description

Disallow template literal placeholder syntax in regular strings.

ECMAScript 6 allows programmers to create strings containing variable or expressions using template literals, instead of string concatenation, by writing expressions like ${variable} between two backtick quotes (`). It can be easy to use the wrong quotes when wanting to use template literals, by writing "${variable}", and end up with the literal value "${variable}" instead of a string containing the value of the injected expressions.

Examples

Invalid

js
const a = "Hello ${name}!";
<pre class="language-text"><code class="language-text">code-block.js:1:18 <a href="https://biomejs.dev/linter/rules/no-template-curly-in-string">lint/suspicious/noTemplateCurlyInString</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: Orange;">⚠</span></strong> <span style="color: Orange;">Unexpected template string placeholder.</span> <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>const a = &quot;Hello $&#123;name&#125;!&quot;; <strong> │ </strong> <strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong> <strong>2 │ </strong> <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Turn the string into a template string.</span> </code></pre>
js
const a = 'Hello ${name}!';
<pre class="language-text"><code class="language-text">code-block.js:1:18 <a href="https://biomejs.dev/linter/rules/no-template-curly-in-string">lint/suspicious/noTemplateCurlyInString</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: Orange;">⚠</span></strong> <span style="color: Orange;">Unexpected template string placeholder.</span> <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>const a = 'Hello $&#123;name&#125;!'; <strong> │ </strong> <strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong> <strong>2 │ </strong> <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Turn the string into a template string.</span> </code></pre>
js
const a = "Time: ${12 * 60 * 60 * 1000}";
<pre class="language-text"><code class="language-text">code-block.js:1:18 <a href="https://biomejs.dev/linter/rules/no-template-curly-in-string">lint/suspicious/noTemplateCurlyInString</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: Orange;">⚠</span></strong> <span style="color: Orange;">Unexpected template string placeholder.</span> <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>const a = &quot;Time: $&#123;12 &#42; 60 &#42; 60 &#42; 1000&#125;&quot;; <strong> │ </strong> <strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong> <strong>2 │ </strong> <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Turn the string into a template string.</span> </code></pre>

Valid

js
const a = `Hello ${name}!`;
const a = `Time: ${12 * 60 * 60 * 1000}`;

const a = templateFunction`Hello ${name}`;
</TabItem> </Tabs>