JavaScript Comments
JavaScript Comments
JavaScript does not have any print object or print methods.You cannot access output devices from JavaScript.The only exception is that you can call the window.print() method in the browser to print the content of the current window.
Single Line Comments
Single line comments start with //. Any text between // and the end of the line will be ignored by JavaScript (will not be executed). This example uses a single-line comment before each code line:
var x = 5; // Declare x, give it the value of 5
var y = x + 2; // Declare y, give it the value of x + 2
Multi-line Comments
Multi-line comments start with /* and end with */. Any text between /* and */ will be ignored by JavaScript. This example uses a multi-line comment (a comment block) to explain the code:
It is most common to use single line comments.Block comments are often used for formal documentation.
Using Comments to Prevent Execution
Using comments to prevent execution of code is suitable for code testing. Adding // in front of a code line changes the code lines from an executable line to a comment. This example uses // to prevent execution of one of the code lines:
//document.getElementById("myH").innerHTML = "My First Page";
document.getElementById("myP").innerHTML = "My first paragraph.";
/*
document.getElementById("myH").innerHTML = "My First Page";
document.getElementById("myP").innerHTML = "My first paragraph.";
*/
