How can I make two of my lines in Chart JS thicker

Question

I have made a chart with Chart JS, as you can see in my fiddle. There are three lines in this chart. I want to have the orange and yellow line to be thicker than it is right

Answer 1

You were close to it !
Actually, the attribute you have to edit is not lineWidth but borderWidth (in the first example of Chart.js docs, you can see the attribute).

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As stated in the example of the MDN doc of lineTo :

Use the beginPath() to begin a path to draw a line on, move the pen with moveTo() and use the stroke() method to actually draw the line.

The line is basically a rectangle with a width of 0. Then the width of the line is calculated using the rectangle border width.

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So you simply have to edit your dataset this way :

datasets: [{
    // ...
    borderWidth: 1 // and not lineWidth
    // ...
}]

I also have updated your fiddle with the edit, and you can see that it is working now.