feat: mangle Infinity (#1385)

CHANGELOG.md

@@ -6,6 +6,20 @@
 
     It's now possible to use `--target=es2021` to target the newly-released JavaScript version ES2021. The only difference between that and `--target=es2020` is that logical assignment operators such as `a ||= b` are not converted to regular assignment operators such as `a || (a = b)`.
 
+* Minify the syntax `Infinity` to `1 / 0` ([#1385](https://github.com/evanw/esbuild/pull/1385))
+
+	The `--minify-syntax` flag (automatically enabled by `--minify`) will now minify the expression `Infinity` to `1 / 0`, which uses fewer bytes:
+
+	```js
+	// Original code
+	const a = Infinity;
+
+	// Output with "--minify-syntax"
+	const a = 1 / 0;
+	```
+
+    This change was contributed by [@Gusted](https://github.com/Gusted).
+
 ## 0.12.9
 
 * Allow `this` with `--define` ([#1361](https://github.com/evanw/esbuild/issues/1361))

internal/js_printer/js_printer.go

@@ -2132,15 +2132,27 @@ func (p *printer) printExpr(expr js_ast.Expr, level js_ast.L, flags printExprFla
 		if value != value {
 			p.printSpaceBeforeIdentifier()
 			p.print("NaN")
-		} else if value == positiveInfinity {
-			p.printSpaceBeforeIdentifier()
-			p.print("Infinity")
-		} else if value == negativeInfinity {
-			if level >= js_ast.LPrefix {
-				p.print("(-Infinity)")
-			} else {
+		} else if value == positiveInfinity || value == negativeInfinity {
+			wrap := (p.options.MangleSyntax && level >= js_ast.LMultiply) ||
+				(value == negativeInfinity && level >= js_ast.LPrefix)
+			if wrap {
+				p.print("(")
+			}
+			if value == negativeInfinity {
 				p.printSpaceBeforeOperator(js_ast.UnOpNeg)
-				p.print("-Infinity")
+				p.print("-")
+			} else {
+				p.printSpaceBeforeIdentifier()
+			}
+			if !p.options.MangleSyntax {
+				p.print("Infinity")
+			} else if p.options.RemoveWhitespace {
+				p.print("1/0")
+			} else {
+				p.print("1 / 0")
+			}
+			if wrap {
+				p.print(")")
 			}
 		} else {
 			if !math.Signbit(value) {

internal/js_printer/js_printer_test.go

@@ -931,3 +931,61 @@ func TestAvoidSlashScript(t *testing.T) {
 	expectPrintedMinify(t, "x = 1 < / script/.exec(y).length", "x=1</ script/.exec(y).length;")
 	expectPrintedMinify(t, "x = 1 << / script/.exec(y).length", "x=1<</ script/.exec(y).length;")
 }
+
+func TestInfinity(t *testing.T) {
+	expectPrinted(t, "x = Infinity", "x = Infinity;\n")
+	expectPrinted(t, "x = -Infinity", "x = -Infinity;\n")
+	expectPrinted(t, "x = (Infinity).toString", "x = Infinity.toString;\n")
+	expectPrinted(t, "x = (-Infinity).toString", "x = (-Infinity).toString;\n")
+	expectPrinted(t, "x = (Infinity) ** 2", "x = Infinity ** 2;\n")
+	expectPrinted(t, "x = (-Infinity) ** 2", "x = (-Infinity) ** 2;\n")
+	expectPrinted(t, "x = ~Infinity", "x = ~Infinity;\n")
+	expectPrinted(t, "x = ~-Infinity", "x = ~-Infinity;\n")
+	expectPrinted(t, "x = Infinity * y", "x = Infinity * y;\n")
+	expectPrinted(t, "x = Infinity / y", "x = Infinity / y;\n")
+	expectPrinted(t, "x = y * Infinity", "x = y * Infinity;\n")
+	expectPrinted(t, "x = y / Infinity", "x = y / Infinity;\n")
+	expectPrinted(t, "throw Infinity", "throw Infinity;\n")
+
+	expectPrintedMinify(t, "x = Infinity", "x=Infinity;")
+	expectPrintedMinify(t, "x = -Infinity", "x=-Infinity;")
+	expectPrintedMinify(t, "x = (Infinity).toString", "x=Infinity.toString;")
+	expectPrintedMinify(t, "x = (-Infinity).toString", "x=(-Infinity).toString;")
+	expectPrintedMinify(t, "x = (Infinity) ** 2", "x=Infinity**2;")
+	expectPrintedMinify(t, "x = (-Infinity) ** 2", "x=(-Infinity)**2;")
+	expectPrintedMinify(t, "x = ~Infinity", "x=~Infinity;")
+	expectPrintedMinify(t, "x = ~-Infinity", "x=~-Infinity;")
+	expectPrintedMinify(t, "x = Infinity * y", "x=Infinity*y;")
+	expectPrintedMinify(t, "x = Infinity / y", "x=Infinity/y;")
+	expectPrintedMinify(t, "x = y * Infinity", "x=y*Infinity;")
+	expectPrintedMinify(t, "x = y / Infinity", "x=y/Infinity;")
+	expectPrintedMinify(t, "throw Infinity", "throw Infinity;")
+
+	expectPrintedMangle(t, "x = Infinity", "x = 1 / 0;\n")
+	expectPrintedMangle(t, "x = -Infinity", "x = -1 / 0;\n")
+	expectPrintedMangle(t, "x = (Infinity).toString", "x = (1 / 0).toString;\n")
+	expectPrintedMangle(t, "x = (-Infinity).toString", "x = (-1 / 0).toString;\n")
+	expectPrintedMangle(t, "x = Infinity ** 2", "x = (1 / 0) ** 2;\n")
+	expectPrintedMangle(t, "x = (-Infinity) ** 2", "x = (-1 / 0) ** 2;\n")
+	expectPrintedMangle(t, "x = ~Infinity", "x = ~(1 / 0);\n")
+	expectPrintedMangle(t, "x = ~-Infinity", "x = ~(-1 / 0);\n")
+	expectPrintedMangle(t, "x = Infinity * y", "x = 1 / 0 * y;\n")
+	expectPrintedMangle(t, "x = Infinity / y", "x = 1 / 0 / y;\n")
+	expectPrintedMangle(t, "x = y * Infinity", "x = y * (1 / 0);\n")
+	expectPrintedMangle(t, "x = y / Infinity", "x = y / (1 / 0);\n")
+	expectPrintedMangle(t, "throw Infinity", "throw 1 / 0;\n")
+
+	expectPrintedMangleMinify(t, "x = Infinity", "x=1/0;")
+	expectPrintedMangleMinify(t, "x = -Infinity", "x=-1/0;")
+	expectPrintedMangleMinify(t, "x = (Infinity).toString", "x=(1/0).toString;")
+	expectPrintedMangleMinify(t, "x = (-Infinity).toString", "x=(-1/0).toString;")
+	expectPrintedMangleMinify(t, "x = Infinity ** 2", "x=(1/0)**2;")
+	expectPrintedMangleMinify(t, "x = (-Infinity) ** 2", "x=(-1/0)**2;")
+	expectPrintedMangleMinify(t, "x = ~Infinity", "x=~(1/0);")
+	expectPrintedMangleMinify(t, "x = ~-Infinity", "x=~(-1/0);")
+	expectPrintedMangleMinify(t, "x = Infinity * y", "x=1/0*y;")
+	expectPrintedMangleMinify(t, "x = Infinity / y", "x=1/0/y;")
+	expectPrintedMangleMinify(t, "x = y * Infinity", "x=y*(1/0);")
+	expectPrintedMangleMinify(t, "x = y / Infinity", "x=y/(1/0);")
+	expectPrintedMangleMinify(t, "throw Infinity", "throw 1/0;")
+}