Mastering TypeScript 3 - Third Edition

Rest parameters

The JavaScript language also allows a function to be called with a variable number of arguments. To illustrate this point, we can make use of a quirk of the JavaScript language. Every JavaScript function has access to a special variable, named arguments, that can be used to retrieve all arguments that have been passed into the function. As an example of this, consider the following JavaScript code:

function testArguments() { 
    if (arguments.length > 0) { 
        for (var i = 0; i < arguments.length; i++ ) { 
            console.log("argument[" + i + "] = " + arguments[i]); 
        } 
    } 
} 
testArguments(1,2,3); 
testArguments("firstArg");

Here, we have defined a function, named testArguments, which does not have any named parameters. Note, though, that we can ...