Javascript监测元素的曝光

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function printTitle(el) {  
try {
var t = el.children[0].children[1].children[0].children[0].innerText
console.log("valid1 hello callback " +new Date() + t);
}
catch(err) {
console.log(err)
}
}

function beginObserve(arg,callback){
console.log("begin add listener "+arg);
var arr = document.querySelectorAll(arg);
var observer = new IntersectionObserver(
function(objs){
for(i = 0; i < objs.length ; i++ ){
const entry1 = objs[i];
try {
if(entry1.target){
var element1 = entry1.target
const attr1 = element1.getAttribute("bigdata_view");
if(attr1 != null && attr1 != "2"){
element1.setAttribute("bigdata_view", "2");
callback(element1);
}
}else{
console.log("invalid1 hello callback " +new Date());
}
}
catch(err) {
console.log(err)
}
}
}, { threshold: 0.95 } );

for (i = 0; i < arr.length; i++) {
const entry = arr[i];
const attr = entry.getAttribute("bigdata_view");
if(attr == null){
observer.observe(entry);
entry.setAttribute("bigdata_view", "1");
}
}
setTimeout(function() {
beginObserve(arg, callback)
},2000);
}


beginObserve('[tracking_id|="search"],[tracking_id|="re"]',printTitle);

制定一个printTitle方法,调用下面的代码就行了

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beginObserve('[tracking_id|="search"],[tracking_id|="re"]',printTitle);