Variables

Syntax rules

• var has the same behavior as in JavaScript and is subject to variable hoisting.

• const and let are supported and have the same behavior as in JavaScript.

• A variable that is assigned a value without being declared becomes a global variable.

• A variable declared without an assigned value has a default value of undefined.

var num = 1;
var str = "hello alipay";
var undef; // undef === undefined
const n = 2;
let s = 'string';
globalVar = 3;

Variable names

Naming convention

Variable names must adhere to the following rules:

• The first character must be a letter (a-z, A-Z) or an underscore (_).

• Subsequent characters can be letters (a-z, A-Z), underscores (_), or numbers (0-9).

Reserved identifiers

Similar to JavaScript, the following identifiers are reserved and cannot be used as variable names:

arguments
break
case
continue
default
delete
do
else
false
for
function
if
Infinity
NaN
null
require
return
switch
this
true
typeof
undefined
var
void
while