如何将对象键转换为大写

Question

I would like to transform lowercase key to uppercase key. But finding my try not works.

what would be the correct approach?

here is my try:

 var obj = { name: "new name", age: 33 } const x = Object.assign({}, obj); for (const [key, value] of Object.entries(x)) { key = key.toUpperCase(); } console.log(x); 

Live Demo

Answer 1

With

key = key.toUpperCase();

Reassigning a variable will almost never do anything on its own (even if key was reassignable) - you need to explicitly to mutate the existing object:

 var obj = { name: "new name", age: 33 } const x = {}; for (const [key, value] of Object.entries(obj)) { x[key.toUpperCase()] = value; } console.log(x); 

You could also use reduce , to avoid the external mutation of x :

 var obj = { name: "new name", age: 33 } const x = Object.entries(obj).reduce((a, [key, value]) => { a[key.toUpperCase()] = value; return a; }, {}); console.log(x);