Algorithm to re-index an array of objects after insertion or drag 'n' drop order change

Question

Assume I have an indexed array of objects, such as these containing lines of a popular folk song ;)

var lyrics = [
  {line : 2, words : \"He\'s a lumberjack          


        

Answer 1

I would totally simplify your entire structure:

Use a native javascript array, instead of storing an extra key (line) use the javascript index as the key, which means javascript (if used properly) will manage it for you, and use less memory.

So we've got an array of strings:

var f = [];
f.push('first');
f.push('third');
f.push('fourth');

// reindex on insert
// lets insert second in the natural place

f.splice(1,0,'second'); // ["first", "second", "third", "fourth"]

// reindex on delete
// lets delete 'third'

f.splice(2,1); // ["first", "second", "fourth"]

etc.