获取所有可用的麦克风- Map不是一个函数。

Question

我有下面的代码来用可用的麦克风填充select

const audioInputSelect = document.querySelector('select#audioSource');

// Updates the select element with the provided set of cameras
function updateMicrophoneList(microphones) {
    console.log(microphones);
    audioInputSelect.innerHTML = '';
    microphones.map(microphone => {
        const microphoneOption = document.createElement('option');
        microphoneOption.label = microphone.label;
        microphoneOption.value = microphone.deviceId;
    }).forEach(microphoneOption => audioInputSelect.add(microphoneOption));
}


// Fetch an array of devices of a certain type
async function getConnectedDevices(type) {
    const devices = await navigator.mediaDevices.enumerateDevices();
    return devices.filter(device => device.kind === type)
}


// Get the initial set of cameras connected
const microphonesList = getConnectedDevices('audioinput');
updateMicrophoneList(microphonesList);

// Listen for changes to media devices and update the list accordingly
navigator.mediaDevices.addEventListener('devicechange', event => {
    const newMicrophoneList = getConnectedDevices('audioinput');
    updateMicrophoneList(newMicrophoneList);
});

我搞错了

VM1759 audio_devices.js:7 Uncaught TypeError: microphones.map is not a function
    at updateMicrophoneList (VM1759 audio_devices.js:7)
    at VM1759 audio_devices.js:24

为什么map不在这里工作？

Answer 1

getConnectedDevices是一个异步函数，意味着它返回一个承诺，而不是一个数组。您可以使用.then函数在实现承诺时更新列表。

getConnectedDevices('audioinput').then(updateMicrophoneList);