[removed] How do I print a message to the error console?

Question

How can I print a message to the error console, preferably including a variable?

For example, something like:

print(\'x=%d\', x);

Answer 1

If you are using Firebug and need to support IE, Safari or Opera as well, Firebug Lite adds console.log() support to these browsers.

Answer 2

function foo() {
  function bar() {
    console.trace("Tracing is Done here");
  }
  bar();
}

foo();

console.log(console); //to print console object
console.clear('console.clear'); //to clear console
console.log('console.log'); //to print log message
console.info('console.info'); //to print log message 
console.debug('console.debug'); //to debug message
console.warn('console.warn'); //to print Warning
console.error('console.error'); //to print Error
console.table(["car", "fruits", "color"]);//to print data in table structure
console.assert('console.assert'); //to print Error
console.dir({"name":"test"});//to print object
console.dirxml({"name":"test"});//to print object as xml formate

To Print Error:- console.error('x=%d', x);

console.log("This is the outer level");
console.group();
console.log("Level 2");
console.group();
console.log("Level 3");
console.warn("More of level 3");
console.groupEnd();
console.log("Back to level 2");
console.groupEnd();
console.log("Back to the outer level");

Answer 3

If you use Safari, you can write

console.log("your message here");

and it appears right on the console of the browser.

Answer 4

To actually answer the question:

console.error('An error occurred!');
console.error('An error occurred! ', 'My variable = ', myVar);
console.error('An error occurred! ' + 'My variable = ' + myVar);

Instead of error, you can also use info, log or warn.

Answer 5

Visit https://developer.chrome.com/devtools/docs/console-api for a complete console api reference

    console.error(object[Obj,....])\

In this case, object would be your error string

Answer 6

To answer your question you can use ES6 features,

var var=10;
console.log(`var=${var}`);