console.count([obj]) places a counter on the object’s value provided as argument. Each time this method is invoked, the counter is increased (with the exception of the empty string ''). A label together with a number is displayed in the debugging console according to the following format:
label represents the value of the object passed as argument and X represents the counter’s value.
An object’s value is always considered, even if variables are provided as arguments:
var o1 = 1, o2 = '2', o3 = "";
console.count(o1);
console.count(o2);
console.count(o3);
console.count(1);
console.count('2');
console.count('');
Displays:
1: 1
2: 1
: 1
1: 2
2: 2
: 1
Strings with numbers are converted to Number objects:
console.count(42.3);
console.count(Number('42.3'));
console.count('42.3');
Displays:
Functions point always to the global Function object:
console.count(console.constructor);
console.count(function(){});
console.count(Object);
var fn1 = function myfn(){};
console.count(fn1);
console.count(Number);
Displays:
[object Function]: 1
[object Function]: 2
[object Function]: 3
[object Function]: 4
[object Function]: 5
Certain objects get specific counters associated to the type of object they refer to:
console.count(undefined);
console.count(document.Batman);
var obj;
console.count(obj);
console.count(Number(undefined));
console.count(NaN);
console.count(NaN+3);
console.count(1/0);
console.count(String(1/0));
console.count(window);
console.count(document);
console.count(console);
console.count(console.__proto__);
console.count(console.constructor.prototype);
console.count(console.__proto__.constructor.prototype);
console.count(Object.getPrototypeOf(console));
console.count(null);
Displays:
undefined: 1
undefined: 2
undefined: 3
NaN: 1
NaN: 2
NaN: 3
Infinity: 1
Infinity: 2
[object Window]: 1
[object HTMLDocument]: 1
[object Object]: 1
[object Object]: 2
[object Object]: 3
[object Object]: 4
[object Object]: 5
null: 1
Empty string or absence of argument
If no argument is provided while sequentially inputting the count method in the debugging console, an empty string is assumed as parameter, i.e.:
> console.count();
: 1
> console.count('');
: 2
> console.count("");
: 3
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