Found 9053 Articles for Front End Technology

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'); });

JavaScript uses a semi-colon (;) to avoid any confusion in code, especially the beginning of a new line.ExampleYou can still use the following to avoid any chaos in the code −return {    'var':myVal } // using semi-colon; (function( $ ) {    // }

In this tutorial, we shall learn how to set the style of the left border with JavaScript. To set the style of the left border in JavaScript, use the borderLeftStyle property. Set the style under this property that you want for the border i.e. solid, dashed, etc. Let us discuss our topic in brief. Using the borderLeftStyl Property With this property, we can set or return the style of the left border of an element. Users can follow the syntax below for using this property. Syntax object.style.borderLeftStyle = style; This syntax allows the required border style to be ... Read More

In this tutorial, we will learn how and why ‘z’[‘toUpperCase’]() works in JavaScript. From the given format, we can say that it calls the toUpperCase() method for the ‘z’ string. It will work the same as the toUpperCase() method, which we invoke by taking any string as a reference. Let’s understand the syntax of the ‘z’[‘toUpperCase’]() below. Syntax let result = 'z'['toUpperCase'](); // returns 'Z', string in upper case The above syntax is same as the below. Example let string = 'z'; let result = string.toUpperCase(); Why does ‘z’[‘toUpperCase’]() work? In JavaScript toUpperCase() method is used to convert ... Read More