Fill an Array with Sequential Values

Discussion

1. Tracy-Gregory Gilmore

   Would the instruction

   const allLines = fillRange(0, numLines - 1);

   not result in an array starting with zero as the first value?
• David Walsh

  Yes, you’re right! I’ve updated the post!
2. Jorge Ortega

   Nice! Thanks to this post I could do this:

   // Array of 24 hours string values ['00'...'23']
   const hours = Array(24).fill().map((item, index) => index < 10 ? 0${index} : ${index})
   
   // Array of 60 minutes string values ['00'...'59']
   const minutes = Array(60).fill().map((item, index) => index < 10 ? 0${index} : ${index})
   
3. Luca Borrione

   Great post! Little contribution:

   const fillRange = (start, end) => {
   	return [...Array(end - start + 1)].map((item, index) => start + index);
   }
   
• Tracy-Gregory Gilmore

  Using an arrow function with a single expression does not require a return statement or statement block. Thus, the line of code above could be reduced to.

  const fillRange = (start, end) => 
     [...Array(end - start + 1)].map((item, index) => start + index);
  
4. Nicolás Casanova

   This is great, but, one question. If I want to have a list with decimals numbers, how can I do it?
   example: 0.1 to 5.0. (resp: 0.1, 0.2, 0.3 … 4.8, 4.9, 5)
   How can I do this?
   Thanks! :D
• MR T-G J GILMORE

  You could always map() the output of fillRange.

  const decimals = fillRange(0, 50).map(int => int / 10);
  
• MR T-G J GILMORE

  That should have been 1 to 51:

  const decimals = fillRange(1, 51).map(int => int / 10);