how do i make this javascript logic + syntax (very simple)

how do i make this javascript logic + syntax (very simple)

Why I am getting true all the time?
var _template_id = "";
if (_template_id != '0' || _template_id!="") {
alert("true")
}else{
alert("false")
}
or even if i set _template_id="0", it still turns out as true...