JS常用模板

选择器

document.querySelectorAll("table#CardSelectTr tr> td:nth-child(2) > a");

document.getElementById("demo").innerHTML = Date();
document.getElementsByClassName("threadlist").style.margin = "0 auto";
document.getElementsByTagName("h1")[0].style.color = "red";
document.getElementById("url").childNodes[1];
document.querySelector(".novellist li a");    //返回文档中匹配指定 CSS 选择器的第一个元素
document.querySelectorAll(".novellist li a");    //返回匹配的所有元素
document.querySelectorAll("td a")[0].innerHTML

div: nth - of -type(3) //CSS 伪类   匹配同类型中的第n个同级兄弟元素

修改元素的样式

[0].style.margin = "0 auto";
[0].style.border = "1px solid #bbb";
[0].style.borderRadius = "5px";
[0].style.padding = "15px";
[0].style.textAlign = "center";
[0].style.color = "red";

// 添加样式表
var x = document.createElement("STYLE");
var t = document.createTextNode("body {color:red}");
x.appendChild(t);
document.head.appendChild(x);

查找元素是否存在

if (document.getElementsByClassName("dialog-fileTreeDialog").length == 1) {
    // 或 !== null
    console.log("发现目标元素");

} else {
    console.log("目标元素未出现");
}

数组遍历

arr.forEach((item,index,array)=>{

})

for (let i = 0; i < arr.length; i++) {
    console.log(arr[i])
}

修改链接打开方式

function changeTarget() {
    document.getElementById('runoob').target = "_blank";
}

标题链接打开方式改为新标签页

var linkTitle = document.querySelectorAll("li .title a");
for (let i = 0; i < linkTitle.length; i++) {
    // console.log(linkTitle[i].target)
    linkTitle[i].target="_blank";
}

无图模式

var imgArr = document.getElementsByTagName("img");
for (let i = 0; i < imgArr.length; i++) {
    // console.log(imgArr[i].)
    imgArr[i].setAttribute("src", "");
    imgArr[i].setAttribute("data-imgurl", "");
}

//var linkArr=new Array();
var linkArr = document.getElementsByTagName("a");
for (let i = 0; i < linkArr.length; i++) {
    linkArr[i].style.backgroundImage="none";
}

var divArr = document.getElementsByTagName("div");
for (let i = 0; i < divArr.length; i++) {
    // console.log(divArr[i].)
    divArr[i].style.backgroundImage="none";
}

小图模式

var imgArr = document.getElementsByTagName("img");
for (let i = 0; i < imgArr.length; i++) {
    // console.log(imgArr[i].)
    imgArr[i].style.width = null;
    imgArr[i].style.maxWidth = "300px"
    imgArr[i].style.height = null;
    imgArr[i].style.maxHeight = "200px"
}