我怎样才能实现类似于 javascript 中的字符串指针的东西？

Question

Is there a concept like a pointer to a string in javascript? Or how would this be done?

let s1 = "hi";
let s2 = "bye";

// I want to write my code like this [,].forEach();
// This is the bit where I want s1 and s2 in the [,] array to actually be pointers to a string
[s1,s2].forEach(s => {if(s.length < 3) s += "*";});

// I want console.log(s1) === "hi*"
// I want console.log(s2) === "bye" (unchanged)

Answer 1

Javascript does not have pointers.

But you can wrap a value in an object and pass references to that object around.

 let s1 = { value: "hi" }; let s2 = { value: "bye" }; [s1,s2].forEach(s => { if(s.value.length < 3) s.value += "*"; }); console.log(s1.value) console.log(s2.value)

That's probably the closest you're going to get to this behaviour.

Answer 2

You cannot reassign individual identifiers unless you specifically reference the identifier. So given

let s1 = "hi";

The only way to make console.log(s1) show something else would be to have a line of code that does

s1 = // something else

And strings are immutable, of course - for a string, you'd have to reassign it, since you can't mutate it.

I suppose you could put the strings into an array or an object, then examine that instead:

 const strings = { s1: 'hi', s2: 'bye', }; for (const [key, str] of Object.entries(strings)) { if (str.length < 3) { strings[key] += '*'; } } console.log(strings.s1);

Answer 3

I think I found a solution myself.

Could anyone comment if this is good practice or not?

It uses the new thing in ES6 where you can assign things [s1, s2] =

let s1 = "hi", s2 = "bye";
[s1, s2] = [s1, s2].map(s => s + (s.length < 3 ? "*" : ""));

Answer 4

In javascript there is no "pointers", and the only way access local variables is through evil function the eval() :

 { let s1 = "hi"; let s2 = "bye"; ["s1","s1"].forEach(s => { let n = eval(s); if (n.length < 3) eval(s + ' += "*"'); }); console.log(s1,s2); }