I have created ploly chart by using js file and the legend text is truncating with more than 15 plots and the legend should be rendered in horizontal position.
Iām no good with js but have experienced a similar issue using the R api. I resolved it by adding and playing with the margin space so there is more room.
In js I believe that is done by adding a parameter like the one below
var layout = {
autosize: false,
width: 500,
height: 500,
margin: {
l: 50,
r: 50,
b: 1000,
t: 100,
pad: 4
},