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Is it posible to know, if my function takes vars?
For example:
function ada (v) {};
function dad () {};
alert(ada.hasArguments()); // true
alert(dad.hasArguments()); // false
544
To check if a parameter is provided to a function, use the strict inequality (! ==) operator to compare the parameter to undefined , e.g. if (param !== undefined) . If the comparison returns true , then the parameter was provided to the function.
Functions can accept more than one argument. When calling a function, you're able to pass multiple arguments to the function; each argument gets stored in a separate parameter and used as a discrete variable within the function.
Our functions should have the minimum number of arguments possible, if it have less than four argument, nice. Put a limit on the argument's number is not the ideal, we should strive to keep them as minimal as we can.
So the correct way to test undefined variable or property is using the typeof operator, like this: if(typeof myVar === 'undefined') .
Yes. The length property of a function returns the number of declared arguments:
alert(ada.length); // 1
alert(dad.length); // 0
The function's length property represents the number of formal parameters. Note that this is not necessarily equal to the number of actual parameters:
function foo(one, two, three) {
return foo.length === arguments.length;
}
foo("test");
foo("test", "test", "test");
Output:
false
true
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