Now, script syntax is usually straightforward, but as with any language, sometimes it's easy to get confused over certain things in script syntax. In this post I'll cover a quick list of common "gotchas" in CFScript, document the proper syntax for each, and finally link to a list of CFScript guides which may help you start writing CFScript today.
Common "Gotchas" in CFScript
- Too many pound signs
- Missing semicolons
- New operators
- Assignment instead of equality operator
- Strict equality operator
Too Many Pound Signs
Don't do this:
if ( #isBroken# ) {
writeOutput( "Hello #name#!" );
writeOutput( #age# );
}
Why not? Because the pound signs are only necessary within strings. I suppose the correct term is "string evaluation", because your variable needs to be evaluated and the contents placed within the string.
Here's the proper syntax for that above example:
if ( isBroken ) {
writeOutput( "Hello #name#!" );
writeOutput( age );
}
For a more detailed writeup, check out Mark Kruger's "Bamboozled by Pound Sign Decisions" blog post.
Missing Semicolons
This is a fairly easy one. Semicolons are used to terminate a CFScript statement, and are required in ACF up to CF2016. Semicolons are optional now in CF2018, as well as Lucee. So if you get a cryptic "Invalid construct. on line x" error, you may want to check your semicolons!
New Operators
If you're using CFML's JS-like syntax, you should use the new JS-like operators as well, no? This is a matter of preference, but I feel that these operators are more "standard" in all languages and a consistent, improved experience for CF devs.
- Instead of
NOT, use! - Instead of
EQ, use== - Instead of
NEQ, use!= - Instead of
GT, use> - Instead of
LT, use< - Instead of
GTE, use>= - Instead of
LTE, use<= - Instead of
OR, use|| - Instead of
AND, use&&
Older tag-based operators:
if ( NOT json.success OR arrayLen(validation.errors) GT 0 ) {
// do something
}
Newer, JS-like operators:
if ( !json.success || arrayLen(validation.errors) > 0 ) {
// do something
}
PS. ArrayLen() always returns a non-negative integer. There's really no need to check that it's greater than zero, because any non-zero integer will evaluate to true in CFML. Whereas zero always evaluates to false. So you can shrink that conditional further like so:
if ( !json.success || arrayLen(validation.errors) ) {
// do something
}
Using the Assignment Operator Instead of Equality Operator
I feel like this is a rite of passage for all developers. If you accidentally use the assignment operator (=) instead of the equality operator (==) in a conditional, you will get some very interesting results.
For example, this code will always print True! in Lucee.
if ( a = 1 ) {
writeOutput("True!");
} else {
writeOutput("False!");
}
That is a tough bug to find, because it looks right upon first scan. So be intentional about how you write your conditionals!
Strict Equality Operator
This is almost trick question - there is no "strict equality" operator in CFML!
So don't do this, because it just won't work:
if ( myVar === "theValue" ) {
// do something
}
If you must enforce a type, use isValid().
CFScript Syntax Guides
I thought I'd put together a quick (non-exhaustive) list of CFScript syntax guides that may help folks on their journey to modern CF. You may want to bookmark a few of these, like Tony Junkes' comparison of tag and script syntax, as well as Ortus' "100 Minutes" full-on CFScript guide, and finally a cheat sheet by Pete Freitag. As you can see, there is a lot of CFScript documentation out there.
- CFML Tag to Script Conversions by Tony Junkes
- CFScript Cheat Sheet by Pete Freitag
- Learn Modern CFML in 100 Minutes by the Ortus Solutions
- CFScript Syntax Guide on CFDocs.org
- Guide to CFScript by Adam Cameron
- CFScript Usage by Adobe
- Using CFScript Statements, also by Adobe
- The CFScript Language, yet another Adobe CFScript guide
Hope this helps - thank you for reading!
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