How do I make an html button change my java functions [closed]

My code (below) is supposed to chronicle if the button is clicked, and register the said click as a certain selection depending on the button pressed. Unfortunately when I check both the item function and itemselector function after clicking one of the buttons, I currently am just getting an undefined value

if (document.querySelector("button name="item1").click) {
  let itemselector = 1; 
}

if (document.querySelector("button name="item2").click) {
  let itemselector=2;   
}

if (document.querySelector("button name="item3").click) {
  let itemselector=3;   
}

function itemselector{
if (itemselector===1) { 
then let item==="item1"
}
if (weaponselector===2) {
then let item==="item2"
}

if (weaponselector===3) {
then let item==="item3"
}