CODEWITHSUNDEEP
javascriptjqueryarrays
user1869421
user1869421

Reputation: 837

Javascript incrementing a list of list

If I have a list like this:

var a=  [['1'[0]],['2'[0]],['3'[0]],['4'[0]]];

and if condition that should another variable be equal to either '1','2','3','4' then to increment the values of their list eg:

for(var i=0; i<a; i++{
 if(a[i] == z) {
   a[i] += z;
    }
}

I know the above code will not work, but how could I get each 'inner' element to incerment?

I'm a javascript novice, so please excuse any errors in the code.

Thanks

Upvotes: 1

Views: 115

Answers (2)

Michael Berkowski
Michael Berkowski

Reputation: 270727

Those innermost arrays are at index [1] of the first set of inner arrays, assuming your array's actual format is:

// Note the commas between the inner elements which you don't have above.
var a = [['1',[0]],['2',[0]],['3',[0]],['4',[0]]];

So you're nearly there, you need to access a[i][1][0] and incrememnt it ++ rather than += z.

Examples:

console.log(a[1][1][0]);
// 0  (at element '2')

// z is the string value you are searching for...
for(var i=0; i < a.length; i++) {
  // Match the z search at a[i][0]
  // because a[i] is the current outer array and [0] is its first element
  if(a[i][0] == z) {
    // Increment the inner array value which is index [i][1][0]
    // Because the 1-element inner array is at [i][1] and its first element is [0]
    a[i][1][0]++;
  }
}

So for z = '2':

// Flattened for readability:
a.toString();
// "1,0,2,1,3,0,4,0"
//-------^^^

Then z = '4':

// This time the '4' element gets incremented
a.toString();
// "1,0,2,1,3,0,4,1"
//-------^^^-----^^^

Here's a demo on jsfiddle...

Update: This is where the updated value resides:

Console example

The Array[1] 0: 1 is the incremented value for z == '4'.

Upvotes: 2

rdiazv
rdiazv

Reputation: 1153

I'm not sure of what you're trying to accomplish, but I think it's something like this:

var lists = {
    '1': [0],
    '2': [0]
};

function incrementList(listKey, value) {
    if (lists[listKey]) {
        lists[listKey] = lists[listKey].map(function(num) {
            return num + value;
        });
    }        
}

incrementList('1', 2);
console.log(lists['1'][0]); // 2

incrementList('1', 4);
console.log(lists['1'][0]); // 6

​

Upvotes: 1

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