1. Get the number of arguments
Get the length argument can be used directly arguments.length, arguments is the argument object is an array type, with a length property represents the number of arguments, like an array may be acquired by the value of the argument index, e.g. arguments [0]
function fun(a, b, c) {
console.log(arguments.length);
console.log(arguments[0]);
}
fun(1, 2, 3);
Console print out the results:
3
1
2. Get the number of parameter
Get the number of parameter in two ways:
2.1 function name .length
function fun(a, b, c) {
console.log(fun.length);
}
2.2 arguments.callee.length
arguments.callee The property is a pointer to the object's function has arguments, whenever function uses the arguments object is created, we have to call the function fun (); then the fun there argumnets, so arguments.callee means It is the current function
function fun(a, b, c) {
console.log(arguments.callee.length);
}