更改函数中的第一个参数

Question

I would like to do something like this:

function start(){
    // Change the first argument in the argument list
    arguments[0] = '<h1>' + arguments[0] + '</h1>';

    // Call log with the new arguments
    // But outputs: TypeError: Illegal invocation
    log.apply(this, arguments);
}

function log(){ 
    console.log(arguments);   
    // should output -> ['<h1>hello<h1>', 'world', '!']
}


start('hello', 'world', '!');

Answer 1

Your code actually works (I just tested in Firefox, latest version).

However, I could imagine that some implementations may have a problem with the arguments object when passing in as value to Function.prototype.apply . So try:

function start(){
    var args = Array.prototype.slice.call( arguments );
    args[0] = '<h1>' + args[0] + '</h1>';

    log.apply(this, args);
}

By invoking Array.prototype.slice on the arguments -object, we create a " true " ECMAscript Array , which we might need as second argument for .apply()