how to create an operator like varinjlim

Question

I want to create an operator with an arrow beneath, like \varinjlim. Writing $\mathop{\mathsf{elts}}\limits_{\longrightarrow}(F)$ gives me roughly what I want, but there is a bigger space over the arrow, and the arrow head is smaller than in \varinjlim. See below.

\documentclass{article}
\usepackage{amsmath}
\begin{document} 
$\mathop{\mathsf{elts}}\limits_{\longrightarrow}(F)$ $\varinjlim(D)$
\end{document}

How can I get the same spacing and arrow size as $\varinjlim$?

Answer 1

Adapted from here and here:

\documentclass{article}
\usepackage{amsmath}
\makeatletter
\newcommand{\injelts}{%
  \mathop{\mathpalette\inj@lts{{\mathsf{elts}}{\rightarrowfill@\textstyle}}}\nmlimits@
}
\def\inj@lts#1#2{\inj@@lts#1#2}
\def\inj@@lts#1#2#3{%
  \vtop{\m@th\ialign{##\cr
    \hfil$#1#2$\hfil\cr
    \noalign{\nointerlineskip\kern1.5\ex@}#3\cr
    \noalign{\nointerlineskip\kern-\ex@}\cr}}%
}
\makeatother
\begin{document} 
$\varinjlim(F)\injelts(F)$
\end{document}