Create truth-table.js

Author: frontdevops

truth-table.js

@@ -0,0 +1,74 @@
+const vals = [
+    ["-Infinity", -Infinity ],
+    ["-1", -1 ],
+    ['"-1"', "-1"],
+    ['""', ""],
+    ["[[]]", [[]] ], 
+    ["[]", [] ], 
+    ["false", false ], 
+    ["0", 0 ],
+    ["null", null ],
+    ['"0"', "0" ], 
+    ["[0]", [0] ], 
+    ["[1]", [1] ],
+    ['"1"', "1" ],
+    ["1", 1 ],
+    ["true", true ],
+    ["Infinity", Infinity ],
+    ["{}", {} ], 
+    ['"false"', "false" ],
+    ['"true"', "true" ],
+    ["undefined", undefined ],
+    ["NaN", NaN ],
+    ["\\t\\r\\n", "\t\r\n"]
+];
+
+const cmp = (v1, v2) => v1 == v2;
+const canvas = document.getElementById("drawCanvas");
+const ctx = canvas.getContext("2d");
+const n = vals.length;
+const r = 20; // diameter of grid squares
+const p = 60; // padding space for labels
+const f = 12; // font size
+
+// color grid cells
+for (let i = 0; i < n; i++) {
+    let v1 = vals[i][1];
+    for (let j = 0; j < n; j++) {
+        let v2 = vals[j][1],
+        		eq = cmp(v1, v2);
+        ctx.fillStyle = eq ? "orange" : "white";
+        ctx.fillRect(p+i*r,p+j*r,r,r);
+    }
+}
+
+// draw labels
+ctx.fillStyle = "black";
+ctx.font = f + "px Helvetica";
+
+for (let i = 0; i < n; i++) {
+    let s = vals[i][0],
+    		w = ctx.measureText(s).width;
+    ctx.save();
+    ctx.translate(p+i*r+r/2-f*0.4,p-w-2);
+    ctx.rotate(3.14159/2);
+    ctx.fillText(s, 0, 0);
+    ctx.restore();
+}
+
+for (let i = 0; i < n; i++) {
+    let s = vals[i][0],
+    		w = ctx.measureText(s).width;
+    ctx.fillText(s, p-w-2, p+i*r+r/2+f*0.4);
+}
+
+// draw grid lines
+ctx.beginPath();
+ctx.strokeStyle = "black";
+for (let i = 0; i <= n; i++) {
+    ctx.moveTo(p+r*i, p);
+    ctx.lineTo(p+r*i, p+r*n);
+    ctx.moveTo(p, p+r*i);
+    ctx.lineTo(p+r*n, p+r*i);
+}
+ctx.stroke();