Should JavaScript function parameters be passed by value (byVal) or by address (byRef)? Share_javascript skills

Regarding the question of "whether JavaScript function parameters are passed by value (byVal) or by address (byRef)", there is a common misunderstanding: "simple types" such as number and string are passed by value, Number, String, Object, Array, etc." Complex type" is pass-by-address.
Isn’t this wrong? Why is there such a misunderstanding? Take a look at these two pieces of code:

Copy the code The code is as follows:

//Cause value passing Imaginary code
function modifyLikeByVal(x){
x = 1;
console.log('x = %d', x);
}
var x = 0;
console.log('x = %d', x); // Output x = 0
modifyLikeByVal(x); // Output x = 1
console.log('x = %d', x ); // Output x = 0 x has not changed!

Copy code The code is as follows:

//Causes the false address transmission The code of
function modifyLikeByRef(x){
x[0] = 4;
x[1] = 5;
x[2] = 6;
console.log('x = [ %s ]', x.join(', '));
}
var x = [1, 2, 3];
console.log('x = [ %s ]' , x.join(', ')); // Output x = [ 1, 2, 3 ]
modifyLikeByRef(x); // Output x = [ 4, 5, 6 ]
console.log( 'x = [ %s ]', x.join(', ')); // Output x = [ 4, 5, 6 ] x has changed!

So, from the above code, we can conclude that "simple type" is passed by value (byVal) as a parameter, and "complex type" is passed by address (byRef) as a parameter.

What’s the problem?

If you carefully observe the two functions, you can find one thing:
In byVal, the parameter x is directly modified: x = 1;
And in byRef, the member of the parameter x is modified: x[0] = 4; x[1] = 5; x[2] = 6;

My guess is that in JavaScript, all variables or members are pointers. When modifying the value of a variable or member, the address of the pointer is actually modified.

So the above code can be explained:

In "byVal":

Copy code The code is as follows:

global { / / represents the global scope, and the following represents the function scope
var x = 0; // Initialize the pointer x and point to the number 0
fun(x) {
x = global.x; // Pass in Parameter global.x; The x pointer address of the fun field points to the number 0
x = 1; // Modify the x pointer address of the fun field to point to the number 1;
} // fun The domain ends, the x pointer in the global domain has not changed
}

In "byRef":

Copy code The code is as follows:

global { // represents the global scope, the following represents the function scope
/*
Initialize the pointer x and point to the array [1, 2, 3]
is actually the three members of x, 0, 1, 2, pointing to 1, 2, 3 respectively;
*/
var x = [1, 2, 3];
fun(x) {
x = global.x; // Pass in the parameter global.x; the x pointer address of the fun field points to the array [1, 2, 3]
/ + = 4;
x[1] = 5;
x[2] = 6;
} // The fun field ends, the x pointer in the global field has not changed, but its three member pointers have been changed , so we see the result we output
}


So how do you explain this code? ? ?

Copy code

The code is as follows:(function(a, b){ arguments [0] = 1;

b = 2;

console.log(arguments, a, b);
})(-1, -2);


only You can say a, b..., which is an alias for arguments[0],...[n].

If there is something wrong, please point it out, thank you.

If you have a better explanation, please share it.