问form.getElementsByName不是一个函数，但document.getElementsByName是一个函数

EN

<form class="needs-submission">
    <input type="hidden" name="id" value="1">
    <input type="text" name="name">
    <input type="button" name="save" value="Save Changes" onclick="saveChanges(this.closest('.needs-submission'))">
</form>

function saveChanges(form) {
    const id = document.getElementsByName('id')[0]
    const name = document.getElementsByName('name')[0]
    const save = document.getElementsByName('save')[0]
}

function saveChanges(form) {
    const id = form.getElementsByName('id')[0]
    const name = form.getElementsByName('name')[0]
    const save = form.getElementsByName('save')[0]
}

Uncaught TypeError: form.getElementsByName is not a function
    at saveChanges
    at HTMLInputElement.onclick

function saveChanges(form) {
    const id = form.getElementsByTagName('input')[0]
    const name = form.getElementsByTagName('input')[1]
    const save = form.getElementsByTagName('input')[2]
}