JavaScript 執行機制(同步、異步、宏任務、微任務)

• macro-task(宏任務)：包括整體代碼script，setTimeout，setInterval
• micro-task(微任務)：Promise，process.nextTick
• Event Loop 事件循環
  
• Event Queue 執行順序
  
• 示例

console.log('1');
setTimeout(function() {
    console.log('2');
    process.nextTick(function() {
        console.log('3');
    })
    new Promise(function(resolve) {
        console.log('4');
        resolve();
    }).then(function() {
        console.log('5')
    })
})
process.nextTick(function() {
    console.log('6');
})
new Promise(function(resolve) {
    console.log('7');
    resolve();
}).then(function() {
    console.log('8')
})

setTimeout(function() {
    console.log('9');
    process.nextTick(function() {
        console.log('10');
    })
    new Promise(function(resolve) {
        console.log('11');
        resolve();
    }).then(function() {
        console.log('12')
    })
})

執行結果：1, 7, 6, 8, 2, 4, 3, 5, 9, 11, 10, 12