Why am I getting Uncaught TypeError: Cannot read property 'length' of undefined if the var is declared?

Question

I am a very beginner in JavaScript and recently I am studying it on a book. I am trying to modify a script from this book that passes a number which is the number of letters in a word, and output the number of combinations of words you would get by scrambling the letters. While the original script lets you pass the number I want to modify it and allow the user to input a word, take it and return the number of words by scrambling the letters. My issue is that, when I run the code, I keep getting this error:

Uncaught TypeError: Cannot read property 'length' of undefined at thingamajig

Why is this happening?

var word = prompt('Word here.');

function thingamajig(word) {
    var facky = 1;
    clunkCounter = 0; //reset the clunkcounter
    if (word.length == 0) {
        display("clank");
    } else if (word.length == 1) {
        display("thunk");
    } else {
        while (word.length > 1) {
            facky = facky * word.length; //multiply facky with size until size is 0. Basically it is caulculating a factorial
            word.length = word.length - 1;
        }
        clunk(facky);
    }
}

function clunk(times) {
    var num = times;
    while (num > 0) {
        display("clunk"); //keep calling display f until it is = 0
        num = num - 1;
    }
}

function display(output) {
    console.log(output);
    clunkCounter = clunkCounter + 1; //How many times the clunck f called the display f?
}

thingamajig();
console.log(clunkCounter);

`thingamajig();` You aren't passing any argument, so `word` is `undefined`. Either pass `word` to it, or remove the argument — CertainPerformance, Oct 11 '19 at 11:51
@Chillin' Because it's a either a typo or a duplicate, depending on your point of view — CertainPerformance, Oct 11 '19 at 11:54
I am sure before I passed thingamajig(word) but got the same mistake. Now it works. Must have modified it and forgot. Thank you. — Andrea D_, Oct 11 '19 at 11:54

score 1 · Accepted Answer · answered Oct 11 '19 at 11:53

Since you are not passing the parameter in thingamajig() function, you can resolve that by changing your first if condition to check !word instead of the length of word like: if (!word)

Something which will look like:

if (!word) {
  display("clank");
} else if (word.length == 1) {
  display("thunk");
} else {
  while (word.length > 1) {
    facky = facky * word.length; //multiply facky with size until size is 0. Basically it is caulculating a factorial
    word.length = word.length - 1;
  }
  clunk(facky);
}

1

Thank you. I got it now! – Andrea D_ Oct 11 '19 at 11:55

Why am I getting Uncaught TypeError: Cannot read property 'length' of undefined if the var is declared?

1 Answers1