Execute function if input contains certain text

Question

$(function() {
    if ($fa.ismod = true) {
        if (document.getElementById("input#message").value = "/msg") {
            alert('tudo okay');
        }
    }
});

This code should do an Alert if input#message contains the text /msg but it returns this:

Uncaught Typeerror: Cannot set Property 'value' of null(...)

Answer 1

The error showing occurred because you tried to assign value to an element that does not exist.

This will validate the value of the HTML element that has the id equal message.

if (document.getElementById("message").value === "/msg") {
    alert('tudo okay');
}

This will validate the element input HTML that has the id equal to message.

if ($("input#message").val() === "/msg") {
    alert('tudo okay');
}

Note the errors I pointed out by comment.