fix lineHeightFactor bug

refs: parallax#3234

Author: Megharth

src/jspdf.js

@@ -3612,7 +3612,14 @@ function jsPDF(options) {
 
     //baseline
     var height = activeFontSize / scope.internal.scaleFactor;
-    var descent = height * (lineHeightFactor - 1);
+    var descent;
+    if (
+      options.lineHeightFactor &&
+      typeof options.lineHeightFactor === "number"
+    )
+      descent = height * (options.lineHeightFactor - 1);
+    else descent = height * (lineHeightFactor - 1);
+
     switch (options.baseline) {
       case "bottom":
         y -= descent;

test/reference/lineHeight.pdf

@@ -0,0 +1,20 @@
+/* eslint-disable no-self-assign */
+/* global describe, it, expect, jsPDF, comparePdf, Button, ComboBox, ChoiceField, EditBox, ListBox, PushButton, CheckBox, TextField, PasswordField, RadioButton, AcroForm */
+
+/**
+ * line height testing
+ */
+
+ describe("Module: Line Height Unit Test", function() {
+    beforeAll(loadGlobals);
+    it('test line height', function() {
+        const doc1 = new jsPDF();
+        doc1.setLineHeightFactor(1.5);
+        doc1.text('Some text', 10, 10, { baseline: 'middle' });
+        comparePdf(doc1.output(), 'lineHeight.pdf', 'lineHeight');
+
+        const doc2 = new jsPDF();
+        doc2.text('Some text', 10, 10, { lineHeightFactor: 1.5, baseline: 'middle' });
+        comparePdf(doc2.output(), 'lineHeight.pdf', 'lineHeight');
+    });
+ });