JavaScript中charAt方法出现错误

Question

I'm working on a small project with javascript. I am using charAt method to get the first character in a line from ace editor. here's my code:

function checkFirstChar (lineNo) {
  var words = lines[lineNo].split(" ");
  var firstChar = words[0].charAt(0);

  if (firstChar == "." || firstChar == "#") {
    return 0;
  }
  else return 1;
}

Where lines is an array or strings, which is extracted from the ace editor. Problem is, this works fine when the first character is '#'. But when the first character is '.', it doesn't take it as a dot '.' Instead, it takes it as a "" (empty string). Can anyone help me out here ? Whats wrong with it ?

Edit: This is how I took the array, lines.

for(var i = 0, lines = new Array(numOfLines); i<numOfLines; i++ ){
        lines[i] = editor.session.getLine(i);
}

Most confusing part is, when I make an alert from words[0], it shows the word with the dot "."

Answer 1

I tried the code. It works perfectly fine for me. Please check the values that are being inserted in your array. I suppose it should work fine. I implemented the following code:

function myFunc() {
  var words = ".sdf dfsf #sdsd df";
  var firstChar = words[0].charAt(0);
  document.getElementById("demo").innerHTML = "";
  if (firstChar == "." || firstChar == "#")
    document.getElementById("demo").innerHTML = "bingo";
}

Answer 2

Instead of using charAt(), you should use your string as a table of chars.

 var firstChar = words[0].charAt(0);

can be replaced by

 var firstChar = words[0][0];