有时候还是用油猴方便，WebDriver考虑的太多
//获取元素，一直查询，直到找到为止，参数名称比较好理解
function getElement(parent, selector, timeout = 0) {
return new Promise(resolve => {
let result = parent.querySelector(selector);
if (result) return resolve(result);
let timer;
const mutationObserver = window.MutationObserver || window.WebkitMutationObserver || window.MozMutationObserver;
if (mutationObserver) {
const observer = new mutationObserver(mutations => {
for (let mutation of mutations) {
for (let addedNode of mutation.addedNodes) {
if (addedNode instanceof Element) {
result = addedNode.matches(selector) ? addedNode : addedNode.querySelector(selector);
if (result) {
observer.disconnect();
timer && clearTimeout(timer);
return resolve(result);
}
}
}
}
});
observer.observe(parent, {
childList: true,
subtree: true
});
if (timeout > 0) {
timer = setTimeout(() => {
observer.disconnect();
return resolve(null);
}, timeout);
}
} else {
const listener = e => {
if (e.target instanceof Element) {
result = e.target.matches(selector) ? e.target : e.target.querySelector(selector);
if (result) {
parent.removeEventListener('DOMNodeInserted', listener, true);
timer && clearTimeout(timer);
return resolve(result);
}
}
};
parent.addEventListener('DOMNodeInserted', listener, true);
if (timeout > 0) {
timer = setTimeout(() => {
parent.removeEventListener('DOMNodeInserted', listener, true);
return resolve(null);
}, timeout);
}
}
});
}
