How does the getelementsbytagname method work in HTML?

The getElementsByTagName () method returns a collection of all elements in the document with the specified tag name, as an HTMLCollection object. The HTMLCollection object represents a collection of nodes. The nodes can be accessed by index numbers. The index starts at 0. Tip: The parametervalue “*” returns all elements in the document.

How to implement ” Select All ” check box in JavaScript?

Here is a solution that selects/unselects checkboxes by class name, using vanilla javascript function document.getElementsByClassName. The Select All button. Select All. Some of the checkboxes to select.

How to find number of elements in HTML collection?

The elements in the returned collection are sorted as they appear in the source code. Find out how many elements there are in the document (using the length property of the HTMLCollection object): document.getElementsByTagName(“P”) [0].innerHTML = “Hello World!”; Using the “*” parameter.

What does the drawimage ( ) method do in HTML?

Definition and Usage The drawImage () method draws an image, canvas, or video onto the canvas. The drawImage () method can also draw parts of an image, and/or increase/reduce the image size. Note: You cannot call the drawImage () method before the image has loaded.

How to draw an image on canvas in JavaScript?

context .drawImage ( img,x,y ); Position the image on the canvas, and specify width and height of the image: JavaScript syntax: context .drawImage ( img,x,y,width,height ); Clip the image and position the clipped part on the canvas: JavaScript syntax: context .drawImage ( img,sx,sy,swidth,sheight,x,y,width,height );

Why is the output of getelementsbytagname undefined?

As in above output for the 5th link (index of an array 4) the output is displaying undefined because the document contains only 4 links which means the return array of document.getElementsByTagName ( “a” ) contain all these “a” (link) elements which starts storing from index 0 to 3.