<!DOCTYPE qhelp PUBLIC
 "-//Semmle//qhelp//EN"
 "qhelp.dtd">
<qhelp>

<overview>
<p>
Template literals are strings enclosed with backticks (<tt>``</tt>). These may
contain placeholder expressions with the syntax <tt>${<em>..</em>}</tt>, which are
evaluated at runtime and inserted as part of the string.
</p>
<p>
Ordinary string literals may be enclosed by single (<tt>''</tt>) or double quotes (<tt>""</tt>),
and the placeholder syntax <tt>${<em>..</em>}</tt> has no special meaning in these.
</p>
<p>
In files that make use of template literals, it is hard to distinguish actual template literals from
ordinary strings that happen to contain placeholder syntax.
This is often the result of mistyping the quotes on a template literal.
</p>
</overview>

<recommendation>
<p>
Consider if this was intended to be a template literal, and if so, change the quotes to backticks (<tt>``</tt>).
Alternatively:
</p>
<ul>
<li>Rename some local variables so that the placeholders do not give the impression of referencing those.</li>
<li>Avoid mixing JavaScript template literals with other template systems in the same file.</li>
</ul> 
</recommendation>

<example>
<p>
In the following example, the call to <tt>log.error</tt> will log the string "<tt>${id}</tt>",
rather than the contents of the <tt>id</tt> variable. 
</p>
<sample src="examples/TemplateSyntaxInStringLiteral.js"/>
<p>
To correct the error message, change the quotes to backticks:
</p>
<sample src="examples/TemplateSyntaxInStringLiteralGood.js"/>
</example>

<references>
<li>Mozilla Developer Network: <a href="https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Template_literals">Template literals</a>.</li>
</references>
</qhelp>