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Welcome to the Javascript-slicing- wiki!

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STILL IN WORK!

In Javascript there exists a method called slice which should enable the coder to select an area of an array content.

The slice method takes either one or two arguments to define in which interval a sample in an array should be taken.

1. Extracting elements with two positive arguments

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In this case the first argument should be the beginning and the second should define the ending of the chosen area. The ending argument which indicates to a value in the array is not included in the resulting slice.

var R = [1,2,3,4,5,6,7,8];

//Doesn`t really slice, because beginning and ending arguments are not valid
console.log( R.slice(2,1) );//Outputs:[]
console.log( R.slice(0,0) );//Outputs:[]

//Legit
console.log( R.slice(0,1) );//Outputs:[1]
console.log( R.slice(1,2) );//Outputs:[2]
console.log( R.slice(2,3) );//Outputs:[3]
console.log( R.slice(3,4) );//Outputs:[4]
console.log( R.slice(4,5) );//Outputs:[5]
console.log( R.slice(5,6) );//Outputs:[6]
console.log( R.slice(6,7) );//Outputs:[7]
console.log( R.slice(7,8) );//Outputs:[8]

2. Extracting elments with two negative arguments

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The negative value -1 seems the index value of the last element. The ending argument which indicates to a value in the array is not included in the resulting slice.

var R = [1,2,3,4,5,6,7,8];

//Doesn`t really slice, because beginning and ending arguments are not valid
console.log( R.slice(-1,-2) );//Outputs:[]

//Legit
console.log( R.slice(0,-1) );//Outputs:[1, 2, 3, 4, 5, 6, 7]
console.log( R.slice(-2,-1) );//Outputs:[7]
console.log( R.slice(-3,-2) );//Outputs:[6]
console.log( R.slice(-4,-3) );//Outputs:[5]
console.log( R.slice(-5,-4) );//Outputs:[4]
console.log( R.slice(-6,-5) );//Outputs:[3]
console.log( R.slice(-7,-6) );//Outputs:[2]
console.log( R.slice(-8,-7) );//Outputs:[1]

3. Extracting elments with one positive argument

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If the ending is not defined, which is the case here, then its default value will be the length of the array.

var R = [1,2,3,4,5,6,7,8];

//Legit
console.log( R.slice(1) );//Outputs:[2, 3, 4, 5, 6, 7, 8]
console.log( R.slice(2) );//Outputs:[3, 4, 5, 6, 7, 8]
console.log( R.slice(3) );//Outputs:[4, 5, 6, 7, 8]
console.log( R.slice(4) );//Outputs:[5, 6, 7, 8]
console.log( R.slice(5) );//Outputs:[6, 7, 8]
console.log( R.slice(6) );//Outputs:[7, 8]
console.log( R.slice(7) );//Outputs:[8]

//Doesn`t really slice, because argument is not valid
console.log( R.slice(0) );//Outputs:[1, 2, 3, 4, 5, 6, 7, 8]
console.log( R.slice(8) );//Outputs:[]

4. Extracting elments with one negative argument

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var R = [1,2,3,4,5,6,7,8];

//LEGIT
console.log( R.slice(-1) );//Outputs:[8]
console.log( R.slice(-2) );//Outputs:[7, 8]
console.log( R.slice(-3) );//Outputs:[6, 7, 8]
console.log( R.slice(-4) );//Outputs:[5, 6, 7, 8]
console.log( R.slice(-5) );//Outputs:[4, 5, 6, 7, 8]
console.log( R.slice(-6) );//Outputs:[3, 4, 5, 6, 7, 8]
console.log( R.slice(-7) );//Outputs:[2, 3, 4, 5, 6, 7, 8]

//Doesn`t really slice, because argument is not valid
console.log( R.slice(-8) );//Outputs:[1, 2, 3, 4, 5, 6, 7, 8]
console.log( R.slice(-9) );//Outputs:[1, 2, 3, 4, 5, 6, 7, 8]

5. Extracted objects refer to the same objects

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//An array with objects
var R =[ {'Hello': 2}, {'How':4}, {'Are':6}, {'You':8}];

//New Array - Contains: "[{'Hello': 2}, {'How':4}]"
var Reference = R.slice(0, 2);

//Overwriting a new value to the object "{'Hello': 2}"
Reference[0]['Hello'] = 10;

//'R' and 'Reference' refer to the same objects which they have within
console.log(Reference[0]);//Outputs: {'Hello': 10}
console.log(R[0]);        //Outputs: {'Hello': 10}

6. Extracting values to a new array is a copy not a reference

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var R = [1,2,3,4,5,6,7,8];

//Contains:[7, 8]
var aCopy = R.slice(-2) ;

//Overwriting value "7"
aCopy[0] = 42;

console.log(aCopy[0]);//Outputs: 42
console.log(R[6]);    //Outputs: 7