change json underline to camp

This is a interview question I encountered, so I'm recording it.

The question is: How to change all the keys of a JSON data from underscore to camel case?

Below is the implementation method during the answer process:

const testData = {
    a_bbb: 123,
    a_g: [1, 2, 3, 4],
    a_d: {
        s: 2,
        s_d: 3
    },
    a_f: [1, 2, 3, {
        a_g: 5
    }],
    a_d_s: 1
}

/**
 * Convert _w to W
 */
function toCame(str) {
    return str.replace(/\_(\w)/g, function(a, b) {
        return b.toUpperCase();
    });
}

/**
 * Change all the keys of a JSON data from underscore to camel case
 * 
 * @param {object | array} value The object or array to be processed
 * @returns {object | array} The processed object or array
 */
function mapKeysToCamelCase(data) {
    if(data instanceof Array) {
        data.forEach(function(v, index) {
            mapKeysToCamelCase(v);
        });
    } else if(data instanceof Object) {
        Object.keys(data).forEach(function(v, index) {
            var newValue = toCame(v);
            console.info(newValue);
            
            // If the names are the same, it means there may be no conversion
            if(newValue != v) {
                data[newValue] = data[v];
                delete data[v];
            }

            // Recursion
            mapKeysToCamelCase(data[newValue]);
        });
    }

    return data;
}

console.log(mapKeysToCamelCase(testData))

Further thinking:

This is directly operating on the original object, how to copy a new object?
ES should have a better method for looping through objects, how to use the new features?

...To be continued