Cannot access default value in Javascript function

Question

I am drawing a triangle with "#" as default value if 'char' is not defined. When I define 'char' I get the triangle drawn with that particular value.

If 'char' is defined then triangle must be drawn in characters from 'char' else it should use default value '#'.

What am I missing or doing wrong?

function triangle(size, char = 0) {

  if (typeof char === 'undefined') {
    let hashKey = "#"
    while (hashKey.length <= size) {
      console.log(hashKey);
      hashKey += "#";
    }
  } else {
    let hashKey = char
    while (hashKey.length <= size) {
      console.log(hashKey);
      hashKey += char;
    }
  }
}

With your default initialiser = 0 on the parameter declaration, char will never be undefined. — Bergi
– Bergi, Commented Oct 18, 2020 at 11:18
char is never undefined. Whenever it gets that value (either by omitting it in the call or explicitly passing undefined), it is automatically assigned the default value 0. So the first branch of your if will never be true. — VLAZ
– VLAZ, Commented Oct 18, 2020 at 11:19
Yes I saw this, thanks, but how else to make it an optional value? — M. El-Set
– M. El-Set, Commented Oct 18, 2020 at 11:19
just don't assign a default value function(triangle, char) { ... or set char to the desired value function triangle (size, char = '#') { ... instead — derpirscher
– derpirscher, Commented Oct 18, 2020 at 11:20

Bergi · Accepted Answer · 2020-10-18 11:22:01Z

3

With your default initialiser = 0 on the parameter declaration, char will never be undefined.

You'll want to write

function triangle(size, char) {
    if (typeof char === 'undefined') {
        char = "#"
    }
    let hashKey = char;
    while (hashKey.length <= size) {
        console.log(hashKey);
        hashKey += char; 
    }
}

or

function triangle(size, char = '#') {
    let hashKey = char;
    while (hashKey.length <= size) {
        console.log(hashKey);
        hashKey += char; 
    }
}

answered Oct 18, 2020 at 11:22

Bergi

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Comments

A_A · Accepted Answer · 2020-10-18 11:21:48Z

1

If you want to assign a default value to char you can do that in the parameter defintion:

function triangle (size, char = '#'){
  let hashKey = char
  while(hashKey.length <= size ){
    console.log(hashKey);
    hashKey += char; 
  }
}
triangle(4)

answered Oct 18, 2020 at 11:21

A_A

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Comments

Seldo97 · Accepted Answer · 2020-10-18 11:27:11Z

0

You don't have to declare 'char' in your parametr when you call a function.

Just make it like 'function triangle (size, char)' and change condition to 'if (!char)'.

answered Oct 18, 2020 at 11:27

Seldo97

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