Is the detection change triggered when default TS/JS Data types methods are called within an HTML template?

I'm currently updating an application where developers originally included function calls directly in the HTML templating, like this:

<span>{{'getX()'}}</span>

This resulted in the getX method being called after each change detection cycle, leading to poor performance. I have since corrected this issue.

However, I am now wondering about using methods on default data types. Will Angular evaluate the result of calling toLowerCase on strings after every change detection cycle?

<span>{{'myString.toLowerCase()'}}</span>

Furthermore, will the get function of a TypeScript Map object be invoked after each change detection cycle as well?

<span>{{'myTSMap.get('key')'}}</span>

If not, would utilizing pipes be the optimal solution for addressing this concern? Thank you.

Answer №1

The evaluation of the entire expression must be performed. There is no distinction between your customized function and the functions provided by the virtual machine (such as those in a web browser).

According to the documentation:

Angular processes all expressions within double curly braces, converts the results of the expressions into strings, and connects them with neighboring literal strings.

(emphasis added)

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