分配 ID 并遍历 Javascript 中的行
Assign Id and iterate through rows in Javascript
我创建了一个 table,它似乎工作正常,但我在为这个 table 分配一个 id 时遇到问题,计算它有多少行,并为每一行分配一个 id。调试器说:
TypeError: document.getElementById(...) is null
我不知道我做错了什么。有人可以帮忙吗?我也在下面的代码中评论了我的问题:
function populateTable(list){
var tableContent = "<table>";
for (var i = 0; i < list.length; ++i) {
var record = list[i];
tableContent += "<tr><td>" + record.Title + "</td></tr>\n";
}
tableContent += "</table>";
tableContent.id="orders";
var rows = document.getElementById("orders").rows.length;//why is this null?
document.getElementById("test").innerHTML = rows;
for (var i=0; i< rows; ++i){
//how do I assign an id for the element here?
}
}
编辑
您似乎不知道如何从 javascript:
正确创建 DOM
http://www.w3schools.com/jsref/met_document_createelement.asp
旧答案
这一行:
var rows = document.getElementById("orders").rows.length;//why is this null?
通过 id 从 HTML 文档中获取元素。看起来您还没有将 tableContent
添加到文档中。
你可以这样做:
HTML:
<div id="here"> </div> <!-- the table will be added in this div -->
JavaScript:
function populateTable(list){
var tableContent = document.createElement('table');
for (var i = 0; i < list.length; ++i) {
var record = list[i];
var cell = document.createElement('td');
var row = document.createElement('tr');
var textnode = document.createTextNode(record.Title);
cell.appendChild(textnode);
row.appendChild(cell);
tableContent.appendChild(row);
}
tableContent.id="orders";
document.getElementById("here").appendChild(tableContent); // the table is added to the HTML div element
var rows = document.getElementById("orders").rows;
for (var i=0; i < rows.length; ++i){
rows[i].id = "myId" + (i+1); // this is how you assign IDs
console.log(rows[i]);
}
}
var persons = [{Title:"John"}, {Title:"Marry"}];
populateTable(persons);
这是我的建议(阅读代码中的注释):
// This will create a table element and return it
function createTable(list){
var table = document.createElement('table'); // This is an actual html element
table.id = 'orders'; // Since it's an html element, we can assign an id to it
tableHtml = ''; // This empty string will hold the inner html of the table we just created
for (var i = 0; i < list.length; ++i) {
var record = list[i];
// we can assign the id here instead of looping through the rows again
tableHtml += '<tr id="row-' + i + '"><td>' + record.Title + '</td></tr>';
}
table.innerHTML = tableHtml; // We insert the html into the table element and parse it
var rows = table.rows.length; // We already have a reference to the table, so no need of getElementById
alert('rows'); // rows holds the number of rows. You can do whatever you want with this var.
return table; // return the table. We still need to insert it into the dom
}
// Create a new table and hold it in memory
var myTable = createTable([{Title:'One'}, {Title:'Two'}, {Title:'Three'}]);
// Inset the newly created table into the DOM
document.getElementById('parent-of-table').appendChild(myTable);
希望对您有所帮助
这已经得到回答,但这是我的版本,没有所有评论:
function createTable(list){
var table = document.createElement('table');
table.id = 'orders';
tableHtml = '';
for (var i = 0; i < list.length; ++i) {
tableHtml += '<tr id="row-' + i + '"><td>' + list[i].Title + '</td></tr>';
}
table.innerHTML = tableHtml;
var rows = table.rows.length;
alert('rows');
return table;
}
我创建了一个 table,它似乎工作正常,但我在为这个 table 分配一个 id 时遇到问题,计算它有多少行,并为每一行分配一个 id。调试器说:
TypeError: document.getElementById(...) is null
我不知道我做错了什么。有人可以帮忙吗?我也在下面的代码中评论了我的问题:
function populateTable(list){
var tableContent = "<table>";
for (var i = 0; i < list.length; ++i) {
var record = list[i];
tableContent += "<tr><td>" + record.Title + "</td></tr>\n";
}
tableContent += "</table>";
tableContent.id="orders";
var rows = document.getElementById("orders").rows.length;//why is this null?
document.getElementById("test").innerHTML = rows;
for (var i=0; i< rows; ++i){
//how do I assign an id for the element here?
}
}
编辑
您似乎不知道如何从 javascript:
正确创建 DOMhttp://www.w3schools.com/jsref/met_document_createelement.asp
旧答案
这一行:
var rows = document.getElementById("orders").rows.length;//why is this null?
通过 id 从 HTML 文档中获取元素。看起来您还没有将 tableContent
添加到文档中。
你可以这样做:
HTML:
<div id="here"> </div> <!-- the table will be added in this div -->
JavaScript:
function populateTable(list){
var tableContent = document.createElement('table');
for (var i = 0; i < list.length; ++i) {
var record = list[i];
var cell = document.createElement('td');
var row = document.createElement('tr');
var textnode = document.createTextNode(record.Title);
cell.appendChild(textnode);
row.appendChild(cell);
tableContent.appendChild(row);
}
tableContent.id="orders";
document.getElementById("here").appendChild(tableContent); // the table is added to the HTML div element
var rows = document.getElementById("orders").rows;
for (var i=0; i < rows.length; ++i){
rows[i].id = "myId" + (i+1); // this is how you assign IDs
console.log(rows[i]);
}
}
var persons = [{Title:"John"}, {Title:"Marry"}];
populateTable(persons);
这是我的建议(阅读代码中的注释):
// This will create a table element and return it
function createTable(list){
var table = document.createElement('table'); // This is an actual html element
table.id = 'orders'; // Since it's an html element, we can assign an id to it
tableHtml = ''; // This empty string will hold the inner html of the table we just created
for (var i = 0; i < list.length; ++i) {
var record = list[i];
// we can assign the id here instead of looping through the rows again
tableHtml += '<tr id="row-' + i + '"><td>' + record.Title + '</td></tr>';
}
table.innerHTML = tableHtml; // We insert the html into the table element and parse it
var rows = table.rows.length; // We already have a reference to the table, so no need of getElementById
alert('rows'); // rows holds the number of rows. You can do whatever you want with this var.
return table; // return the table. We still need to insert it into the dom
}
// Create a new table and hold it in memory
var myTable = createTable([{Title:'One'}, {Title:'Two'}, {Title:'Three'}]);
// Inset the newly created table into the DOM
document.getElementById('parent-of-table').appendChild(myTable);
希望对您有所帮助
这已经得到回答,但这是我的版本,没有所有评论:
function createTable(list){
var table = document.createElement('table');
table.id = 'orders';
tableHtml = '';
for (var i = 0; i < list.length; ++i) {
tableHtml += '<tr id="row-' + i + '"><td>' + list[i].Title + '</td></tr>';
}
table.innerHTML = tableHtml;
var rows = table.rows.length;
alert('rows');
return table;
}