Use the addEventListener() method to attach an event handler.ExampleYou can try to run the following code to learn how to work with addEventListener() method in JavaScript −           Double click the below button.       Double Click                      document.getElementById("btnid").addEventListener("dblclick", displayEvent);          function displayEvent() {             document.getElementById("pid").innerHTML = Date();          }          

The fastest and pure JavaScripr Graph visualization toolkit isJavaScript InfoVis Toolkit. With it, you can, Perform Graph manipulation, Create bar graphs, Custom nodes, Implementing NodeTypes Adding subtrees, Drag and drop nodes, etc.

To create a new img tag in JavaScript, pass an HTML string to the constructor,var myImg = $(''); $(document.createElement(myImg)); myImg.attr('src', responseObject.imgurl);You can also use the following code to create a new img tag with the attributes like src, id, etc −var myImg = $('', {    id: 'id1',    src: exampleimg.png',    alt: 'Alt text' });

HTML contains special characters such as ‘, ’ ‘/, ’ and many more such as single and double commas. These special characters are used for the HTML tag, such as ‘’ is used to close the HTML tag. This tutorial teaches us to escape HTML special characters in JavaScript.Now, the question is that what if we want to use these characters inside the HTML content? If we use special characters normally in the HTML content, it considers it the opening or closing HTML tag and produces an unknown error.For example, we need to render the below string to the browser. ... Read More

The isNan() method is used in JavaScript to check whether there’s the existence of an undefined value or can say checks for a NaN object. ExampleTo check whether a JavaScript date is valid or not, you can try to run the following code −                    var date1, date2;          date1 = new Date("2018/1/1");          if( ! isNaN ( date1.getMonth() )) {             document.write("Valid date1: "+date1);          } else {             document.write("Invalid date1");          }          date2 = new Date("20181/1");          if( ! isNaN ( date2.getMonth() )) {             document.write(" Valid date2: "+date2);          } else {             document.write("Invalid date2");          }           The isNaN(null) == false is semantically correct. This is because null is not NaN.

Try any of the following for the width of the image you want to create −myImg.setAttribute('width', '5px');OrmyImg.width = '5';OrmyImg.style.width = '5px';You can also try the following code to add the width and height to the background image −var myImg = new Image(5,5); myImg.src = 'http://www.example.com';

Yes, use new RegExp(pattern, flags) to achieve this in JavaScript.You can try to run the following code to implement JavaScript regex using string variables −                    var str = 'HelloWorld'.replace( new RegExp('hello', 'i'), '' );          document.write(str);          

To get only the else part, just negate, using ! the operator in JavaScript. You can try to run the following code to achieve this −var arr = {}; if (!(id in arr)) { } else { }In addition, if you want the existence of a property in an object, then use hasOwnProperty −if (!arr.hasOwnProperty(id)) { } else { }

To create a syntax-highlighting code with JavaScript, use the prettify library. Add the following in your code to add the library for syntax highlighting −To use it, add the following to your tag −    Code comes here

Use the keydown event in JavaScript to get to know which keys are pressed at once. The following is the script −Examplevar log = $('#log')[0],    keyPressed = []; $(document.body).keydown(function (evt) {    var li = keyPressed [evt.keyCode];    if (!li) {       li = log.appendChild(document.createElement('li'));       keyPressed [evt.keyCode] = li;    }    $(li).text(Key Down: ' + evt.keyCode);    $(li).removeClass('key-up'); }); $(document.body).keyup(function (evt) {    var li = keyPressed [evt.keyCode];    if (!li) {       li = log.appendChild(document.createElement('li'));    }    $(li).text('Key Up: ' + evt.keyCode);    $(li).addClass('key-up'); });