How to Interpolate Normal Values in JavaScript Tagged Template Strings

Discover a simple method for interpolating normal values in JavaScript tagged template strings while keeping the other variables intact!
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Interpolating Normal Values in JavaScript Tagged Template Strings

JavaScript's tagged template strings provide developers with a way to manage and manipulate strings with great flexibility. By utilizing template literals, you can interpolate variables into strings seamlessly, which is particularly useful when working with libraries such as Lit. However, there may be occasions where you need to treat certain variables as normal text without triggering the standard interpolation behavior. This guide will explore how to achieve that workaround.

The Problem with Tagged Template Strings

Tagged template strings allow developers to create complex templates and manipulate variables easily. For example, when using Lit, you might create a string like this:

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This would output:

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But what if you wanted to interpolate a variable while keeping its value untouched? For instance, consider the following code snippet:

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In this case, the goal is to treat main_site_header_level as a simple string rather than a variable that triggers interpolation. Unfortunately, the traditional method won't work, and you might find yourself needing a different strategy.

The Solution: Using a Customized Immediate Function

To handle this requirement, we can create a specialized function that allows for two levels of template processing. This function will differentiate between immediate values (that you want to output directly) and the rest that will be passed to the original tag function.

Step-by-Step Breakdown of the Solution

Define the Custom Tag Function: Start by creating your tag function, which in this case acts like the Lit html function.

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Create the Immediate Function: Next, implement the immediate function that processes values as specified.

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Use the Functions: Finally, utilize the immediate function to achieve the desired interpolation.

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Understanding the Output

When the above code is executed, it produces two distinct outputs:

The first call to the html function processes the string with the usual tag behavior:

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The second call through immediate(html) specifically handles the immediate values, so the output looks like this:

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This demonstrates that the main_site_header_level variable was treated as plain text, as intended, without triggering unnecessary interpolation.

Conclusion

Using tagged template strings in JavaScript is a powerful tool, especially when working with libraries like Lit. However, when you need to treat certain variables as normal text, the method outlined above allows for that flexibility. By employing a custom function that differentiates immediate values from regular interpolated values, you can maintain the intended structure of your templates without losing their dynamic capabilities.

Armed with this information, you can elevate your usage of tagged template strings and create more complex and customizable outputs in your code. Happy coding!