Add highestHeadingLevel

README.md

@@ -49,6 +49,7 @@ export default Example;
 | -------------------- | ----------------- | ----------------------------------------------------------------------------- |
 | `markdownText`       | string            | **Required** The markdown text you want to creat a TOC from.                  |
 | `titleLimit`         | number            | The maximum length of each title in the TOC.                                  |
+| `highestHeadingLevel` | number            | The highest level of headings you want to extract from the given markdownText. |
 | `lowestHeadingLevel` | number            | The lowest level of headings you want to extract from the given markdownText. |
 | `className`          | strig             | Your custom className.                                                        |
 | `type`               | "deafult" or"raw" | The type of a TOC you want to use.                                            |

src/__tests__/utils.test.ts

@@ -34,17 +34,30 @@ describe("extractHeadingsFromMd", () => {
   `;
 
   it("It extracts headings from the given markdownText.", () => {
-    expect(extractHeadingsFromMd(markdownText, 3)).toEqual([
+    expect(extractHeadingsFromMd(markdownText, 1, 3)).toEqual([
       "# Heading1\n",
       "## Heading2\n",
       "### Heading3\n"
     ]);
   });
 
   it("It extracts headings from the given markdownText.", () => {
-    expect(extractHeadingsFromMd(markdownText, 2)).toEqual([
+    expect(extractHeadingsFromMd(markdownText, 1, 2)).toEqual([
       "# Heading1\n",
       "## Heading2\n"
     ]);
   });
+
+  it("It extracts headings from the given markdownText.", () => {
+    expect(extractHeadingsFromMd(markdownText, 2, 3)).toEqual([
+      "## Heading2\n",
+      "### Heading3\n"
+    ]);
+  });
+
+  it("It extracts headings from the given markdownText.", () => {
+    expect(extractHeadingsFromMd(markdownText, 2, 2)).toEqual([
+      "## Heading2\n"
+    ]);
+  });
 });

src/index.tsx

@@ -12,6 +12,10 @@ interface Props {
     The maximum length of each title in the TOC.
   */
   titleLimit?: number;
+  /*
+    The highest level of headings you want to extract from the given markdownText.
+  */
+  highestHeadingLevel?: number;
   /*
     The lowest level of headings you want to extract from the given markdownText.
   */
@@ -39,6 +43,7 @@ interface Props {
 const Toc = ({
   markdownText,
   titleLimit,
+  highestHeadingLevel,
   lowestHeadingLevel,
   className,
   type
@@ -47,15 +52,16 @@ const Toc = ({
   const limit = titleLimit ? titleLimit : 200;
   const defaultClass = type === "raw" ? "" : "react-toc";
   const customClass = className || defaultClass;
-  const headingLevel: number = lowestHeadingLevel || 6;
+  const headingLevels: number[] = [highestHeadingLevel || 1, lowestHeadingLevel || 6];
 
   // Style settings
   const style: string | undefined = styles[customClass] || className;
 
   // Mutate headings
   const matchedHeadings: RegExpMatchArray | null = extractHeadingsFromMd(
     markdownText,
-    headingLevel
+    headingLevels[0],
+    headingLevels[1]
   );
   const headingObjects = matchedHeadings?.map(heading =>
     newHeading(heading, limit)

src/utils.ts

@@ -25,10 +25,11 @@ const createTitle = (string: string, stringLimit: number) => {
 // It extracts headings from the given markdownText.
 const extractHeadingsFromMd = (
   markdownText: string,
-  numberOftargetHeadings: number
+  highestTargetHeadings: number,
+  lowestTargetHeadings: number
 ): RegExpMatchArray | null => {
   const headingRegex = new RegExp(
-    `^#{1,${numberOftargetHeadings}}\\s.+\\n`,
+    `^#{${highestTargetHeadings},${lowestTargetHeadings}}\\s.+\\n`,
     "gm"
   );
   return markdownText.match(headingRegex);