gtm-javascript

This skill ensures all JavaScript code generated for Google Tag Manager (GTM) Custom HTML tags is ES5-compliant and follows current best practices (2024-2025).

GTM's JavaScript compiler operates in ES5 (ECMAScript 5) mode by default. ES6+ syntax causes compilation errors and prevents tag publishing.

| Variables | const, let | var | | Functions | () => {} | function() {} | | Strings | ` ${var} | 'str' + var` | | Destructuring | {a, b} = obj | var a = obj.a | | Spread | [...arr] | arr.concat() | | Default params | fn(x = 1) | x = x \|\| 1 | | for-of | for (x of arr) | for (var i...) | | Classes | class Foo {} | function Foo(){} |