The TRIANGLE_STRIP is suppose look like the one in the document (https://p5js.org/reference/#/p5/beginShape).
But, when I tried in WEBGL it look different, some points are not connected to each other. (https://alpha.editor.p5js.org/binkpitch/sketches/HJkNCBEBQ).
Is this intended in WEBGL?
p5js’ WEBGL is a work-in-progress; and thus incomplete & buggy!
Better report that issue there: