Difference Between Two Adjacent Numbers In Array

I start my adventure with AngularJS and I have a question, is it possible to calculate the difference between two numbers? After extracting data from SQL - I get a table like this,

Solution 1:

I think its in the scope of simple javascript.

If you have your data in an array just use a simple iteration on it and compare the visit of current day to the visits from previous day.

A very simple solution might be:

var visitsArr = [38,29,18,29,28,18,24];

checkVisitsDiff(visitsArr);


functioncheckVisitsDiff(arr){
  //Input validation check if(!arr || arr.length <2){
     throw"Bad input!";
  }

  //If input is ok - Start from second elementfor(var i=1; i<arr.length; i++){
      var currentElement  = arr[i];
      var previousElement = arr[i-1];
      console.log("The difference from visit " + i + " to visit " +(i-1) + " is: " +(currentElement-previousElement));
  }
}

I hope this what you asked.

Solution 2:

Use Array methods:

var visitsArr = [38,29,18,29,28,18,24];

var diffs = visitsArr.slice(1).map((x,i)=> x-visitsArr[i]);

diffs.forEach((x,i) =>console.log(
   `Visits from day ${i+1} to day ${i+2} increased by ${x}`
));

For more information, see

• MDN JavaScript Reference - Array.slice
• MDN JavaScript Reference - Array.map
• MDN JavaScript Reference - Array.forEach