I use the following code for open webpage inside the HTML page. 
but its opening in another tab instead of that html page.
I need to open google webpage inside of the HTML body instead of another tab?
23 Answers
In your HTML you might have something like
<body> <iframe src=""></iframe> </body> Then in your function
var url = ' document.getElementById('myIframe').src = url; <!DOCTYPE html> <html> <body> <iframe src=""> <p>Your browser does not support iframes.</p> </iframe> </body> </html> Look at w3school for this simple information.
I am guessing you trying open new page using _self. Try to add "_self" as next parameter in open. Read more here
Try following code
var Url = ""; window.open(Url, "_self");