13af6ab5fSopenharmony_ci# The comma operator ``,`` is supported only in ``for`` loops 23af6ab5fSopenharmony_ci 33af6ab5fSopenharmony_ciRule ``arkts-no-comma-outside-loops`` 43af6ab5fSopenharmony_ci 53af6ab5fSopenharmony_ci**Severity: error** 63af6ab5fSopenharmony_ci 73af6ab5fSopenharmony_ciArkTS supports the comma operator ``,`` only in ``for`` loops. Otherwise, 83af6ab5fSopenharmony_ciit is useless as it makes the execution order harder to understand. 93af6ab5fSopenharmony_ci 103af6ab5fSopenharmony_ci 113af6ab5fSopenharmony_ci## TypeScript 123af6ab5fSopenharmony_ci 133af6ab5fSopenharmony_ci 143af6ab5fSopenharmony_ci``` 153af6ab5fSopenharmony_ci 163af6ab5fSopenharmony_ci for (let i = 0, j = 0; i < 10; ++i, j += 2) { 173af6ab5fSopenharmony_ci console.log(i) 183af6ab5fSopenharmony_ci console.log(j) 193af6ab5fSopenharmony_ci } 203af6ab5fSopenharmony_ci 213af6ab5fSopenharmony_ci let x = 0 223af6ab5fSopenharmony_ci x = (++x, x++) // 1 233af6ab5fSopenharmony_ci 243af6ab5fSopenharmony_ci``` 253af6ab5fSopenharmony_ci 263af6ab5fSopenharmony_ci## ArkTS 273af6ab5fSopenharmony_ci 283af6ab5fSopenharmony_ci 293af6ab5fSopenharmony_ci``` 303af6ab5fSopenharmony_ci 313af6ab5fSopenharmony_ci for (let i = 0, j = 0; i < 10; ++i, j += 2) { 323af6ab5fSopenharmony_ci console.log(i) 333af6ab5fSopenharmony_ci console.log(j) 343af6ab5fSopenharmony_ci } 353af6ab5fSopenharmony_ci 363af6ab5fSopenharmony_ci // Use explicit execution order instead of the comma operator: 373af6ab5fSopenharmony_ci let x = 0 383af6ab5fSopenharmony_ci ++x 393af6ab5fSopenharmony_ci x = x++ 403af6ab5fSopenharmony_ci 413af6ab5fSopenharmony_ci``` 423af6ab5fSopenharmony_ci 433af6ab5fSopenharmony_ci 44