how can I check if a variable brought as a string is a number or letter in Javascript?

Question

I was trying to check a value that cames as a string is actually a string or a number and tried this:

let k = "a5b";
for(var i = 0; i < k.length; i++){
  var currentVal = k[i]
  if(typeof currentVal != " number"){
    console.log(currentVal + " is a letter")
  }
  else{
    console.log("its a number")
  }

}

But, it didn't work. I'm trying to implement this approach to check if a returned value in the form of a string is a number or a word. How could I make it detect wether there is actually a number inside or not?

I'm guessing that `k` would be a value from an input and you want to check if it's a number or not. — Camilo, Feb 06 '20 at 03:44

score 2 · Accepted Answer · answered Feb 06 '20 at 03:41

2

I've fixed, check it..

let k = "a5b";
for(var i = 0; i < k.length; i++){
  var currentVal = k[i]
  if(isNaN(currentVal)){
    console.log(currentVal + " is a letter")
  }
  else{
    console.log("its a number")
  }
}

answered Feb 06 '20 at 03:41

chandu komati

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score 1 · Answer 2 · answered Feb 06 '20 at 03:36

One option is to use the Number constructor and compare that to the value itself.

let k = "a5b";
for(var i = 0; i < k.length; i++){
  var currentVal = k[i]
  if(Number(currentVal) != currentVal){
    console.log(currentVal + " is a letter")
  }
  else{
    console.log("its a number")
  }

}

how can I check if a variable brought as a string is a number or letter in Javascript?

2 Answers2