如何处理输入字符串不允许数字或符号的错误

Question

I'm going through an exercise and one of the functions is to write code that takes an input containing only strings and returns the first non-repeating character. I've done that already, but i would like to make it smarter by handling any errors that could be a number or symbol. I tried all I could but it seems not to work. It should be purely letters and spaces taken.

Here is what I have so far.

function TheOutput(word){
  var a =word.length;          
  for(var i=0;   i < a;  i++){
  var char=word.charAt(i);
  if(word.indexOf(char)===word.lastIndexOf(char)){
    result = (char + " is not a number <br/>");                
    break;
  }
  return result;
  }
}

Answer 1

You can use regular expressions if you want to test if string is containing only letters and spaces.

var onlyLettersAndSpace = 'Valid string';
var stringWithNumbers = 'Invalid string 123';
var RegExpression = new RegExp(/^[a-zA-Z\s]*$/);
console.log(RegExpression.test(onlyLettersAndSpace));
// true
console.log(RegExpression.test(stringWithNumbers));
// false

In your case, you could do something like:

function testWord(word) {
    var RegExpression = new RegExp(/^[a-zA-Z\s]*$/);
    return RegExpression.test(word);
}

You can do a lot more with regular expressions, see RegExp MDN: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp