Change key name in JavaScript object

Question

I am checking the attributes in a JavaScript object, replacing some of the keys by deleting the prefix \"element\" and saving the new values in another object.

Answer 1

The problem is that you are looking for the property in the original object using the new key. Use keys[j] instead of key:

var keys = Object.keys(json);
for (var j=0; j < keys.length; j++) {
   var key = keys[j].replace(/^element_/, "");
   tmp[key] = json[keys[j]];
}

I uses a regular expression in the replace so that ^ can match the beginning of the string. That way it only replaces the string when it is a prefix, and doesn't turn for example noexample_data into no_data.

Note: What you have is not "a json", it's a JavaScript object. JSON is a text format for representing data.

Is that due to the fact that I converted the keys (Objects) to Strings (with the replace method)?

No. The keys are strings, not objects.

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You could also change the properties in the original object by deleting the old ones and adding new:

var keys = Object.keys(json);
for (var j=0; j < keys.length; j++) {
   if (keys[j].indexOf("element_") == 0) {
     json[keys[j].substr(8)] = json[keys[j]];
     delete json[keys[j]];
   }
}