getelementsbytagname is returning wrong values

Question

I’m trying to make an HTML table selectable, when I try to get the table rows by getElementsByTagName(), is returning different values when reloading the page.

My Table:

Javascript:

var tabela = document.getElementById("listSensors");
var linhas = tabela.getElementsByTagName("tr");
console.log(linhas);
console.log(linhas.length);

Returns:

It seems to me it’s something to do with running time, some suggestion to resolve?

Answer 1

Enter your javascript code before closing the tag </body> to ensure that all HTML content has been loaded. Also, use the event onload to ensure that javascript runs after loading.

window.onload = function() {
    var tabela = document.getElementById("listSensors");
    var linhas = tabela.getElementsByTagName("tr");
    console.log(linhas);
    console.log(linhas.length);
};