JavaScript method to dynamically add columns_javascript skills
The example in this article describes the method of dynamically adding columns in JavaScript. Share it with everyone for your reference. The specific implementation method is as follows:
/*** * 动态添加table 列 * @param result */ function addRow(resultJson){ /* var temp = []; temp = $.grep(arr, function(val, key) { if(val.indexOf('c') != -1) return true; // 如果[invert]参数不给或为false, $.grep只收集回调函数返回true的数组元素 // 反之[invert]参数为true, $.grep收集回调函数返回false的数组元素 }, false); console.dir(temp); */ if(resultJson!=""){ var cv_arr=new Array(); var date_arr = new Array(); //将数据源解析,并解析成程序可认的date及result $.each(resultJson, function(index, val) { if(val['parser_schedule']!=null){ cv_arr.push(val['parser_schedule']); var temp_data =val['parser_schedule'].split(","); for(i=0;i<temp_data.length;i++){ var temp = temp_data[i].split(":"); date_arr.push(temp[0]); } } }); date_arr = unique(date_arr); date_arr.in_arr = function(value) { var a = this; //为了增加方法扩展适应性。我这稍微修改了下 for (var i = 0; i < a.length; i++) { if (a[i] == value) return i; } } //ARR下标值从0开始 var old_td_n = $("#mytable thead tr").find("th").length; //获取已有的TH //设置TH信息 for(i=0;i<date_arr.length;i++){ //注意TH和TD,样式不一样 $("#mytable thead tr").append("<th>"+date_arr[i]+"</th>"); $("#mytable tbody tr").append("<td>-</td>"); } var rowNum_arr=new Array(); //获取一共有多少行 for(i=0;i<$("#mytable").find("tr").length;i++){ //获取每一行中第三列的值,table前两列隐藏,第三列开始判断是否有数据 var str=$("#mytable tbody").find("tr").eq(i); var std=str.find("td").eq(2); //当没有值的时候记录,获取行号 if($.trim(std.text()).length <1){ rowNum_arr.push(i); }else{ // $(std).html(""); } } //设置TD信息 for(i=0;i<cv_arr.length;i++){ //获取RESULT_ARR中的日期数据 var temp_str = cv_arr[i];//OK //将日期数据用","分割成数组 var temp_arr = temp_str.split(",");//OK [03-11:10,03-12:9,03-13:8,03-14:15] for(j=0;j<temp_arr.length;j++){ //获取数据集 为字符串例如03-11:10 var temp_result = temp_arr[j]; /* 将数据集分割为数组[03-11:10] ARR[0] 03-11 ARR[1] 10 */ var temp_result_arr = temp_result.split(":"); //设置第I行的TR里的内容 $("#mytable tbody").find("tr").eq(rowNum_arr[i]).find("td").eq(old_td_n+date_arr.in_arr(temp_result_arr[0])).html(temp_result_arr[1]); // 应用样式 $("#tb tr:even td").addClass("alt");//行的颜色 $("#tb tr").find("td:eq(2)").addClass("spec"); $("#tb tr:even").find("td:eq(2)").addClass("specalt"); } } } }
I hope this article will be helpful to everyone’s JavaScript programming design.

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The main uses of JavaScript in web development include client interaction, form verification and asynchronous communication. 1) Dynamic content update and user interaction through DOM operations; 2) Client verification is carried out before the user submits data to improve the user experience; 3) Refreshless communication with the server is achieved through AJAX technology.

Understanding how JavaScript engine works internally is important to developers because it helps write more efficient code and understand performance bottlenecks and optimization strategies. 1) The engine's workflow includes three stages: parsing, compiling and execution; 2) During the execution process, the engine will perform dynamic optimization, such as inline cache and hidden classes; 3) Best practices include avoiding global variables, optimizing loops, using const and lets, and avoiding excessive use of closures.

Python is more suitable for beginners, with a smooth learning curve and concise syntax; JavaScript is suitable for front-end development, with a steep learning curve and flexible syntax. 1. Python syntax is intuitive and suitable for data science and back-end development. 2. JavaScript is flexible and widely used in front-end and server-side programming.

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