Ответ

Promise.resolve()

 .then(() => setTimeout(() => console.log('var_1'), 0))

 .then(() => console.log('var_2'))

 .then(() => console.log('var_3'))

Promise.resolve()

 .then(() => console.log('var_4'))

 .then(() => console.log('var_5'))

 .then(() => console.log('var_6'))

4-2-5-3-6-1