javascript - DOM 编辑 chrome 扩展,只显示滚动后的 DOM 变化?
问题描述
我做了一个 chrome 扩展,将 IMDB 信息添加到 Netflix 电影和电视节目中。我是网络开发的新手,我这样做是为了学习和练习我的 JS。扩展工作和收视率被添加到电影/电视节目信息页面,但除非我稍微滚动一下,否则它们几乎总是不会出现。我已经发布了我的代码,以及演示这一点的视频。
https://imgur.com/a/6pCCDpN(请注意在我滚动之前不会出现评级)
//manipulates the DOM to extract the title and year of a video, then calls appropriate function
function fetchMovieNameYear() {
var synopsis = document.querySelectorAll('.jawBone .jawbone-title-link');
//console.log(synopsis);
// If synopsis is null returns undefined
if (synopsis === null) {
console.log('Synopsis not found');
return;
}
//returns a nodelist containing the appropriate div
var logoElement = document.querySelectorAll('.jawBone .jawbone-title-link .title');
//if logoElement has no memebers, returns undefined
if (logoElement.length === 0){
return;
}
//logoElement is now just the div containing the img that has the title
logoElement = logoElement[logoElement.length - 1];
//Extract the actual Title of the Film or TV Show
var title = logoElement.querySelector(".logo").getAttribute("alt");
//Nodelist containing year of the video
var yearElement = document.querySelectorAll('.jawBone .jawbone-overview-info .meta .year');
//if yearElement has no members, returns undefined
if (yearElement.length === 0){
console.log('YearElement Not found');
return;
}
var year = yearElement[yearElement.length - 1].textContent;
var divId = getDivId(title, year);
var divEl = document.getElementById(divId);
//If rating has already been added for this element, it exits the function
if (divEl && (divEl.offsetWidth || divEl.offsetHeight || divEl.getClientRects().length)) {
return;
}
var existingImdbRating = window.sessionStorage.getItem(title + ":" + year);
if ((existingImdbRating !== "undefined") && (existingImdbRating !== null)) {
addIMDBRating(existingImdbRating, title, year);
} else {
makeRequestAndAddRating(title, year)
}
};
//parses imdbMetaDeta, creates a div with rating and votecount info, and adds it to the DOM
function addIMDBRating(imdbMetaData, name, year) {
var divId = getDivId(name, year);
//console.log(divId);
var divEl = document.getElementById(divId);
//If rating has already been added for this element, it exits the function
if (divEl && (divEl.offsetWidth || divEl.offsetHeight || divEl.getClientRects().length)) {
return;
}
var synopsises = document.querySelectorAll('.jawBone .synopsis');
if (synopsises.length) {
var synopsis = synopsises[synopsises.length - 1];
var div = document.createElement('div');
var imdbRatingPresent = imdbMetaData && (imdbMetaData !== 'undefined') && (imdbMetaData !== "N/A");
var imdbVoteCount = null;
var imdbRating = null;
var imdbId = null;
if (imdbRatingPresent) {
var imdbMetaDataArr = imdbMetaData.split(":");
imdbRating = imdbMetaDataArr[0];
imdbVoteCount = imdbMetaDataArr[1];
imdbId = imdbMetaDataArr[2];
}
var imdbHtml = null;
if((imdbRating!=="undefined")||(imdbVoteCount!=="undefined")){
imdbHtml = 'IMDb rating : ' + "<strong>" + (imdbRatingPresent ? imdbRating : "N/A")+"</strong>" +"<br>" + "Vote Count : " +"<strong>" + (imdbVoteCount ? imdbVoteCount : "N/A")+"</strong>";
}else{
imdbHtml = "IMDb rating : <strong>Rare_Issue</strong> <br> Vote Count : <strong>Rare_issue</strong> ";
}
if (imdbId !== null && (imdbId !== 'undefined')) {
imdbHtml = "<a style='color:#f3ce13;' target='_blank' href='https://www.imdb.com/title/" + imdbId + "'>" + imdbHtml + "</a>";
}
div.style.color = "#f3ce13";
div.innerHTML = imdbHtml;
div.className = 'imdbRating';
div.id = divId;
synopsis.parentNode.insertBefore(div, synopsis);
}
}//Creates an Id for the Div that will contain the rating information. Used later on to reduce multiple rating inputs
function getDivId(name, year) {
name = name.replace(/[^a-z0-9\s]/gi, '');
name = name.replace(/ /g, '');
return "aaa" + name + "_" + year;
}
//Makes API call, gets metadata about move/show and calls addImdbRating
function makeRequestAndAddRating(name, year) {
var url = "https://www.omdbapi.com/?i=tt3896198&apikey=70106a0a" + "&t=" +encodeURI(name)
+ "&y=" + year + "tomatoes=true";
var xhr = new XMLHttpRequest();
xhr.open('GET', url);
xhr.withCredentials = true;
//xhr.setRequestHeader('Content-Type', 'application/json');
xhr.onload = function () {
if (xhr.status === 200) {
var apiResponse = JSON.parse(xhr.responseText);
//var metaScore= apiResponse["metaScore"];
var imdbRating = apiResponse["imdbRating"];
var imdbVoteCount = apiResponse["imdbVotes"];
var imdbId = apiResponse["imdbID"];
var imdbMetaData = imdbRating + ":" + imdbVoteCount + ":" + imdbId;
window.sessionStorage.setItem(name + ":" + year, imdbMetaData);
// window.sessionStorage.setItem("metaScore:" + name + ":" + year, metaScore)
//window.sessionStorage.setItem("rotten:" + name + ":" + year, rottenRating);
addIMDBRating(imdbMetaData, name, year);
// addRottenRating(rottenRating, name, year);
// addMetaScore(metaScore, name, year);
}
};
xhr.send();
}
//Calls fetchMovieNameYear when the user clicks the chevron on the video thumbnail
if (window.sessionStorage !== "undefined") {
var target = document.body;
// create an observer instance
var observer = new MutationObserver(function (mutations) {
mutations.forEach(function (mutation) {
window.setTimeout(fetchMovieNameYear, 5);
});
});
// configuration of the observer:
var config = {
attributes: true,
childList: true,
characterData: true
};
observer.observe(target, config);
}
新代码如下:
function debounce(func, wait, immediate) {
var timeout;
return function() {
var context = this, args = arguments;
var later = function() {
timeout = null;
if (!immediate) func.apply(context, args);
};
var callNow = immediate && !timeout;
clearTimeout(timeout);
timeout = setTimeout(later, wait);
if (callNow) func.apply(context, args);
};
};
var myEfficientFn = debounce(fetchMovieNameYear(), 250);
window.addEventListener('MutationEvent', myEfficientFn);
//Calls fetchMovieNameYear when the user clicks the chevron on the video thumbnail
if (window.sessionStorage !== "undefined") {
var target = document.body;
// create an observer instance
var observer = new MutationObserver(function (mutations) {
myEfficientFn();
});
// configuration of the observer:
var config = {
attributes: true,
childList: true,
characterData: true
};
observer.observe(target, config);
}
enter code here
解决方案
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