window.onload = function() {
// Сюда ваш код
}я не совсем понял вопроса.
Зачем нужны const и let ? Если всегда был var
let arr = [0]
let arr = [1]Uncaught SyntaxError: Identifier 'arr' has already been declaredvar arr = [0]
var arr = [1]let a = [];
(function () {
for (let i = 0; i < 5; i++) {
a.push( () => i );
}
} ());
console.log(a.map( f => f() )); // [0, 1, 2, 3, 4]// ...
for (var i = 0; i < 5; i++) {
// ...
console.log(a.map( f => f() )); // [5, 5, 5, 5, 5]let ACCELERATION_GRAVITY = 9.806.
function User() {
this.firstname = '';
this.surname = '';
this.setFirstName = function(name) {
this.firstname = name
}
this.setSurname = function(name) {
this.surname = name
}
this.getFullName = function() {
return this.firstname + ' ' + this.surname;
}
}
var user = new User();
user.setFirstName("Петя");
user.setSurname("Иванов");
alert(user.firstname) // Петя
var user2 = new User();
user2.setFirstName('Фёдор');
user2.setSurname("Марков");
alert(user2.firstname) // Федор