使用转发器值Javascript最小化数组

Question

I'm trying to do something interesting in JavaScript, but I can't. This is my input:

 var Input = ['a','a','a','b','b','b','b','c','c','c','a','a','c','d','d','d'];

So my output is that only get differents values and go in a new vector.

 var Output = SomeFunction(Input);

This is what I want:

Output = ['a','b','c','a','c','d'];

Y tried with this, but don't work aswell:

function SomeFunction(input){
var out= [];
 for (var i = 0; i < input.length - 1; i++) {
  if(input[i] == input[i+1]){
   out.push(input[i]);       
  }
 }
 return out;
}

Answer 1

You can use filter()

 var input = ['a', 'a', 'a', 'b', 'b', 'b', 'b', 'c', 'c', 'c', 'a', 'a', 'c', 'd', 'd', 'd']; input = input.filter(function(v, i, arr) { return arr[i - 1] !== v; //compare with the previous value }) document.write(JSON.stringify(input)); 

Answer 2

Try like this

var out= [];
var i = 0;
 for (i = 0; i < input.length - 1; i++) {
  if(input[i] != input[i+1]){
   out.push(input[i]);       
  }
 }
if (out[out.length-1] !== input[i]) 
   out.push(input[i]);     

Answer 3

You can use backreferencing regex

1. Convert the array to string by using join , so that regex can be used on it
2. Use backreferencing regex to remove the consecutive elements with replace()
3. Convert back the string to array using split

(\\w)\\1* Explanation

 var input = ['a', 'a', 'a', 'b', 'b', 'b', 'b', 'c', 'c', 'c', 'a', 'a', 'c', 'd', 'd', 'd']; var str = input.join(''); input = str.replace(/(\\w)\\1*/g, '$1').split(''); console.log(input); document.write('<pre>' + JSON.stringify(input, 0, 2) + '</pre>'); 

Answer 4

You can do a filter like

 var Input = ['a', 'a', 'a', 'b', 'b', 'b', 'b', 'c', 'c', 'c', 'a', 'a', 'c', 'd', 'd', 'd', 'e']; var Output = SomeFunction(Input); function SomeFunction(input) { var out = input.filter(function(value, i) { return value !== input[i + 1] }); return out; } output.innerHTML = JSON.stringify(Output) 

 <pre id="output"><pre> 

Answer 5

 var Input = ['a','a','a','b','b','b','b','c','c','c','a','a','c','d','d','d']; var Output = SomeFunction(Input); function SomeFunction(input){ var out= []; for (var i = 1; i < input.length; i++) { if(input[i] != input[i-1]){ out.push(input[i-1]); } } out.push(input[input.length - 1]); return out; } alert(Output); 

Answer 6

How about this:

 var Input = ['a', 'a', 'a', 'b', 'b', 'b', 'b', 'c', 'c', 'c', 'a', 'a', 'c', 'd', 'd', 'd']; function SomeFunction(input) { var out = []; var initStr = input[0]; console.log(initStr) for (var i = 1; i < input.length; i++) { if (input[i] === initStr) { } else { out.push(input[i - 1]); initStr = input[i]; } } out.push(input[i - 1]); console.log(out); } SomeFunction(Input) 

Answer 7

Example using array filters.

Pretty simple as long as the array is not too large and could rather easily be extended to compare some property in an array of objects. With a larger array it might be faster though to do a for loop instead as in some of the other answers.

 var Input = ['a', 'b', 'c','a', 'b', 'a', 'b', 'c','c'] var Output = Input.filter(function(value,index) { return Input[index - 1] != value; }); 

Answer 8

function SomeFunction(input) {
var out= [];
   out.push(input[i]);         
   for (var i = 0; i < input.length - 1; i++) {
      if(input[i] !== out[out.length-1]){
         out.push(input[i]);         
      }
   }
   return out;
}

Answer 9

Worked for me:

function SomeFunction(input){
var out= [];
 for (var i = 0; i < input.length; i++) {
  if(input[i] !== input[i+1]){
   out.push(input[i]);       
  }
 }
 return out;
}

Be careful with the name of the varible "input". It's not "Input", it's "input".