In Liquid markup, the if, elsif, and else tags are fundamental to Liquid markup and are essential components for conditional logic.

if

The if tag creates simple conditional logic, and is composed of two basic pieces: the condition and the output.

The condition and the output are arranged like so:

{% if condition %} 
    output 
{% endif %}

The condition sets the logical requirements for the output’s appearance. If the condition evaluates to true, the output appears, otherwise, it does not.

Consider the following example:

{% if {{app_program}} == 'Art' %} 
    Welcome to Slate University's Fine Arts Program!
{% endif %}

The condition, if {{app_program}} == 'Art', is saying:

• If the value for the app_program export is Art, then output Welcome to Slate University’s Fine Arts Program!.

• If the value in the condition statement is not Art, then output nothing.

{% endif %}

Every opened tag must have its closing tag: for if, that closing is {% endif %}.

📝 Without the closing tag, the conditional statement won’t function as intended.

elsif

The elsif tag is another basic component in Liquid markup that goes one step further than if: it allows for the evaluation of multiple conditions.

elsif functions much like the if tag; however, unlike the if tag, it can not be used as a standalone tag. It must always be preceded by an if.

An elsif tag, just like an if tag, is composed of a condition and output, but in this case, there may be multiple conditions and multiple outputs.

Consider the following example:

{% if {{app_program}} == 'Art' %} 
    Welcome to Slate University's Fine Arts Program! 
{% elsif  {{app_program}} == 'Medicine' %}
    Welcome to Slate University's School of Medicine!
{% endif %}

This set of conditions can be translated as:

• If the value for the app_program export is Art, then output Welcome to Slate University’s Fine Arts Program!.

• If that’s not the case, but the value for the app_program export is instead Medicine, then output Welcome to Slate University’s School of Medicine!.

• If neither condition is true, then output nothing.

Multiple elsif tags

You can use as many elsif tags as you need.

At some point though, especially in the case of programs or majors, it can be more beneficial to use merge fields and Configurable Joins to dynamically display the value, rather than using Liquid markup to account for every possibility.

else

The else tag is also not a standalone component and must be accompanied by an if statement.

else is a final or catchall tag. The else tag does not have a condition, like the if tag and elsif tags, and must be placed at the end of the full statement.

There are two ways of using the else tag in Liquid markup.

The first:

{% if {{app_program}} == 'Art' %} 
    Welcome to Slate University's Fine Arts Program! 
{% else %} 
    Welcome to Slate University! 
{% endif %}

This can be translated as:

• If the value for the app_program export is Art, then output Welcome to Slate University’s Fine Arts Program!.

• If it doesn’t have that value, just output Welcome to Slate University!.

The second:

{% if {{app_program}} == 'Art' %} 
    Welcome to Slate University's Fine Arts Program! 
{% elsif {{app_program}} == 'Medicine' %} 
    Welcome to Slate University's School of Medicine! 
{% elsif {{app_program}} == 'Biology' %} 
    Welcome to Slate University's School of Science! 
{% else %} 
    Welcome to Slate University! 
{% endif %}

This second example can be translated as:

• If the value for the app_program export is Art, then output Welcome to Slate University's Fine Arts Program!.

• If that’s not the case, but the value for the app_program export is instead Medicine, then output Welcome to Slate University's School of Medicine!.

• If that’s not the case, but the value for the app_program export is instead Biology, then output Welcome to Slate University's School of Science!.

• If none of these conditions is true, output Welcome to Slate University!.

The second of these examples can become cumbersome if there are a large number of different values to evaluate. In some cases, it may be more beneficial and efficient to use merge fields to display information dynamically.

📖 Further reading: See the Shopify documentation on conditional tags.