easy-copy

Copy some properties of an object easily 中文文档

Install

By npm

$ npm install easy-copy

By bower

$ bower install easy-copy

Usage

easyCopy(src [, filter [, opt]])

• src: The source object, where all of the props comes from
• filter: The filter condition, it could be a String, Array, or an Object, and they could be nested deeply
• opt: The options for copy operation

Get Start

If you often write some code like this:

const data = {
    name: body.name,
    age: body.age,
    major: body.major,
    email: body.email
}

You must fell tired very much. How can we do if we use easy-copy?

// Import easy-copy module
const easycopy = require('easy-copy');
 
const data = easycopy(body, ['name', 'age', 'major', 'email']);
// Yes! Just write an array :)

Deeply copy

If an object is nested like this:

const foo = {
  id: 1,
  children: [
    { id: 2, children: [] },
    {
      id: 3,
      children: [
        { id: 4, children: [] },
        { id: 5, children: [] }
      ]
    },
    { id: 6, children: [] }
  ]
}

We can process this object easily using easy-copy. For example, if we just want to keep the second property of the children property, we can do like this:

const bar = easycopy(foo, {children: 1})
 
console.log(bar);
// {
//   children: [
//     {
//       id: 3,
//       children: [
//         { id: 4: children: [] },
//         { id: 5: children: [] }
//       ]
//     }
//   ]
// }

OK, but if I want copy the 2 properties which id is 4 and 5, how can I do? You can write like this:

const baz = easycopy(foo, {children: [{1: {children: 0}}, 2]});
 
console.log(baz);
// {
//   children: [
//     {
//       children: [
//         { id: 4, children: [] }
//       ]
//     },
//     { id: 6, children: [] }
//   ]
// }

Yeah! It's so easy!

Options

The third argument of easycopy() is options. At present, the v1.0 version is support only one option: undefined. it could transform the non existed prop of src object set to undefined automatically. The default value is true, in other words, it relay on the filter argument to set the target properties.

Here are some example:

const foo = {
  a: 1,
  b: 2,
  c: {
    d: 1,
    e: 2
  }
}
 
const bar = easycopy(foo, [{c: ['d', 'z']}, {f: 'h'}]);
// {
//   c: {
//     d: 1,
//     z: undefined
//   },
//   f: {
//     h: unfined
//   }
// }
 
const baz = easycopy(foo, [{c: ['d', 'z']}, {f: 'h'}], {undefined: false});
// {
//   c: {
//     d: 1,
//   },
// }

So you can decide how to filter and copy an object by your self, and you will not meet with some error like Cannot read property 'xxx' of undefined, it is so nasty, isn't it?

Licence

MIT