JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id="links">qsdf qsdf qsdf</textarea>

JavaScript

var defaultHeight = $('#links').height();

$('#links').focusin(function() {
    $('#links').animate({
        height: '100px'
    }, 300, function() {
        // done
    });
});

$('#links').focusout(function() {
    $('#links').animate({
        height: defaultHeight
    }, 300, function() {
        // done
    });
});