Why you should care
Conditional Comments are designed exclusively for Internet Explorer (IE), and hence they operate greatly in that specific browser as these comments are suited to give special instructions that are only meant for IE. As a result, conditional comments are considered a hindrance when run in a browser, other than IE, and should not appear in the code.
Business Impacts
Conditional Comments are not accessible as they exclusively work in Internet Explorer. This greatly reduces the code’s potential to be accessible and productive.
CAST Recommendations
How we detect
var f = function () {
/*@cc_on if (@_jscript) { return 2* @*/ 3; /*@ } @*/
};
Conditional Comments hinder automated tools as they can vary the JavaScript syntax tree at runtime.
Conditional compilation is allowed outside comment, but should strongly avoided as it may cause an invalid syntax for other browser than IE.
About CAST and Highlight’s Code Insights
Over the last 25 years, CAST has leveraged unique knowledge on software quality measurement by analyzing thousands of applications and billions of lines of code. Based on this experience and community standards on programming best practices, Highlight implements hundreds of code insights across 15+ technologies to calculate health factors of a software.