defo
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A method_missing(or Hash.new) lib for JavaScript
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# Defo
[](https://travis-ci.org/alsotang/defo)
A method_missing(or Hash.new) lib for JavaScript.
Defo pronounce 'default' without /t$/.
## Installation
`npm install defo`
## Quick Examples
Set default value with a literal JS Object
```javascript
var Defo = require('defo');
var defo = new Defo('@@@');
console.log(defo.get('notExist')); // => '@@@'
console.log(defo.get('lol<3')); // => '@@@'
```
More advanced, with a Function
```javascript
var Defo = require('defo');
var defo = new Defo(function (key) {
return key + '!!!';
});
console.log(defo.get('Hello')); // => Hello!!!
```
To see more(and more advanced) examples, please visit:
[More Examples](https://github.com/alsotang/defo/blob/master/test/defo.test.js)
## Documentation
* #initialize
* #set
* #get
* #toObject
### #initialize
Defo can be initialized when create a new Defo instance
With literal object:
```javascript
var defo = new Defo({a: 1, b: 2});
var defo2 = new Defo([1, 2, 3]);
```
With a function:
```js
var defo = new Defo(function (key) {
var value = ...// dosomething with key
return value;
});
```
### #set && get
```js
var defo = new Defo();
defo.set('person', {name: 'Alsotang', age: 21});
defo.get('person').height = 1.80;
console.log(defo.get('person')); // => { name: 'Alsotang', age: 21, height: 1.8 }
console.log(defo.get('<3')); // => undefined
```
chaining set
```js
var defo = new Defo();
defo
.set('person', {name: 'Alsotang', age: 21})
.set('pet', {name: 'Piglet', age: 3});
defo.get('person').height = 1.80;
console.log(defo.toObject());
// output:
// { person: { name: 'Alsotang', age: 21, height: 1.8 },
// pet: { name: 'Piglet', age: 3 } }
```
set with a Hash
```js
var defo = new Defo();
defo.set({
name: 'Alsotang',
age: 21
});
defo.get('name').should.equal('Alsotang'); // => true
defo.get('age').should.equal(21); // => true
```
### #toObject
toObject would convert your Defo to a JavaScript Object.
This method will create a new object instead of modify Defo object.
```js
var person = new Defo();
person
.set('name', 'Alsotang')
.set('age', 21);
var pet = new Defo();
pet
.set('name', 'Piglet')
.set('age', 3);
var house = new Defo();
house
.set('person', person)
.set('pet', pet);
console.log(house.toObject());
// output:
// { person: { name: 'Alsotang', age: 21 },
// pet: { name: 'Piglet', age: 3 } }
```
## Memoize
```js
var fibonacci = new Defo(function (key) {
if (key === 1 || key === 2) {
this.set(key, 1);
return this.get(key);
}
this.set(key, this.get(key - 1) + this.get(key - 2));
return this.get(key);
});
fibonacci.get(15).should.equal(610); // 610 is 15-th of fibonacci sequence
fibonacci.get(20).should.equal(6765);
fibonacci._backed.should.eql({ '1': 1, '2': 1, '3': 2, '4': 3,
'5': 5, '6': 8, '7': 13, '8': 21, '9': 34, '10': 55,
'11': 89, '12': 144, '13': 233, '14': 377, '15': 610,
'16': 987, '17': 1597, '18': 2584, '19': 4181,
'20': 6765 });
```
## Why I create Defo
In my work, there are lots of situations to deal with data structure transformation.
For example, there is some rows from SQL database:
```js
var ROWS = [
// Name, Height, Weight, Country
["Alsotang", 180, 60, "Chinese"],
["YB", 165, 50, "Chinese"],
["Jack", 179, 70, "American"],
["Lucy", 170, 100, "American"]
];
```
and I need to transform it to below:
```js
var RESULTS = {
"Chinese": {
"Alsotang": {
"Height": 180,
"Weight": 60
},
"YB": {
"Height": 165,
"Weight": 50
}
},
"American": {
"Jack": {
"Height": 179,
"Weight": 70
},
"Lucy": {
"Height": 170,
"Weight": 100
}
}
};
```
With Defo, I can just write:
```js
var result = new Defo( // in this Defo, key would be Chinese or American
new Defo( // would be Alsotang or Jack in this
new Defo() // Height or Weight
)
);
ROWS.forEach(function (person) {
var name = person[0],
height = person[1],
weight = person[2],
country = person[3];
result.get(country).get(name)
.set('Height', height)
.set('Weight', weight);
});
result.toObject().should.eql(RESULTS); // => true
```
And it works! Otherwise the implement code is ugly, especially when the data structure is not such simple.
## License
MIT http://rem.mit-license.org