I\'ve read this question about javascript trim, with a regex answer.
Then I expect trim to remove the inner space between Hello and World.
You can use Strings replace method with a regular expression.
"Hello World ".replace(/ /g, "");
The replace() method returns a new string with some or all matches of a pattern replaced by a replacement. The pattern can be a string or a RegExp
RegExp
/ / - Regular expression matching spaces
g - Global flag; find all matches rather than stopping after the first match
const str = "H e l l o World! ".replace(/ /g, "");
document.getElementById("greeting").innerText = str;