position() error

[yuleiQ]

when I call position(), display error, but I don't know why

window.addEventListener('scroll', () => {
      this.drawPosition();
    }, true);

drawPosition() {
      if (this.lines && this.lines.length) {
        this.lines.forEach(line => {
          line.position();
        });
      }
    },

[anseki]

Hi @yuleiQ, thank you for the comment. The this.lines seems to contain undefined. Your code has a bug maybe. However, of course I didn't read other parts of your code. For example, that checks this.lines.length wastefully, you can replace the line with:

      if (this.lines) {

Because the .forEach() method does nothing when the array is empty.

[anseki]

This may help you: https://jsfiddle.net/xqd92ke8/

[yuleiQ]

Hi @yuleiQ, thank you for the comment. The this.lines seems to contain undefined. Your code has a bug maybe. However, of course I didn't read other parts of your code. For example, that checks this.lines.length wastefully, you can replace the line with:

      if (this.lines) {

Because the .forEach() method does nothing when the array is empty.

I tried, it seems that it is not because of the error here, because my lines are an array

[anseki]

Try this example code: https://github.com/anseki/leader-line/issues/386#issuecomment-1369781207 The forEach() problem is another problem of your code. That doesn't throw an error but it makes wrong behavior wastefully.

[anseki]

No reply came, then this abandoned issue is closed.