diff --git a/README.md b/README.md
index d9d4bd0b..acd53c9f 100644
--- a/README.md
+++ b/README.md
@@ -10,6 +10,7 @@
 * [Default Options](#default-options)
 * [Available Reports](#available-reports)
 * [Multiprocessing Support](#multiprocessing-support)
+* [onEnd Hook](#onend-hook)
 * [Compare Reports](#compare-reports)
 * [Compare Workflows](#compare-workflows)
 * [Collecting Istanbul Coverage Data](#collecting-istanbul-coverage-data)
@@ -129,6 +130,37 @@ const coverageResults = await coverageReport.generate();
 console.log(coverageResults.summary);
 ```
 
+## onEnd Hook
+For example, checking thresholds:
+```js
+const EC = require('eight-colors');
+const coverageOptions = {
+    name: 'My Coverage Report',
+    outputDir: './coverage-reports',
+    onEnd: (coverageResults) => {
+        const thresholds = {
+            bytes: 80,
+            lines: 60
+        };
+        console.log('check thresholds ...', thresholds);
+        const errors = [];
+        const { summary } = coverageResults;
+        Object.keys(thresholds).forEach((k) => {
+            const pct = summary[k].pct;
+            if (pct < thresholds[k]) {
+                errors.push(`Coverage threshold for ${k} (${pct} %) not met: ${thresholds[k]} %`);
+            }
+        });
+        if (errors.length) {
+            const errMsg = errors.join('\n');
+            console.log(EC.red(errMsg));
+            // throw new Error(errMsg);
+            // process.exit(1);
+        }
+    }
+}
+```
+
 ## Compare Reports
 | | Istanbul | V8 | V8 to Istanbul |
 | :--------------| :------ | :------ | :----------------------  |
@@ -245,13 +277,15 @@ And also there are some problems about counting the functions and branches:
 functions.forEach(block => {
     block.ranges.forEach((range, i) => {
         if (block.isBlockCoverage) {
-            // v8-to-istanbul: count range as branch here. 
+            // v8-to-istanbul: new CovBranch() 
             // Problem: not every block is branch, and the first block is actually function.
             if (block.functionName && i === 0) {
-                // v8-to-istanbul: count range as function here. 
+                // v8-to-istanbul: new CovFunction()
+                // Problem: no anonymous function
             }
         } else if (block.functionName) {
-            // v8-to-istanbul: count range as function here. 
+            // v8-to-istanbul: new CovFunction()
+            // Problem: no anonymous function
         }
     }
 });
diff --git a/lib/converter/converter.js b/lib/converter/converter.js
index c789b413..02742ae6 100644
--- a/lib/converter/converter.js
+++ b/lib/converter/converter.js
@@ -5,9 +5,17 @@
  *   @false means that there is a single range and its count is the number of times the function was called.
  *   @true means that the ranges form a tree of blocks representing how many times each statement or expression inside was executed.
  *        It detects skipped or repeated statements. The root range counts the number of function calls.
- *
  * @functionName can be an empty string. This is common for the FunctionCov representing the whole module.
  */
+// https://github.com/bcoe/v8-coverage
+/**
+* @ranges is always non-empty. The first range is called the "root range".
+* @isBlockCoverage indicates if the function has block coverage information.
+    If this is false, it usually means that the functions was never called.
+    It seems to be equivalent to ranges.length === 1 && ranges[0].count === 0.
+* @functionName can be an empty string. This is common for the FunctionCov representing the whole module.
+*/
+
 // if you have a line of code that says `var x= 10; console.log(x);` that's one line and 2 statements.
 
 const path = require('path');
diff --git a/test/test-v8.js b/test/test-v8.js
index fce90c72..51f953e2 100644
--- a/test/test-v8.js
+++ b/test/test-v8.js
@@ -24,6 +24,28 @@ const coverageOptions = {
 
     // v8Ignore: false,
 
+    onEnd: (coverageResults) => {
+        const thresholds = {
+            bytes: 80,
+            lines: 60
+        };
+        console.log('check thresholds ...', thresholds);
+        const errors = [];
+        const { summary } = coverageResults;
+        Object.keys(thresholds).forEach((k) => {
+            const pct = summary[k].pct;
+            if (pct < thresholds[k]) {
+                errors.push(`Coverage threshold for ${k} (${pct} %) not met: ${thresholds[k]} %`);
+            }
+        });
+        if (errors.length) {
+            const errMsg = errors.join('\n');
+            console.log(EC.red(errMsg));
+            // throw new Error(errMsg);
+            // process.exit(1);
+        }
+    },
+
     outputDir: './docs/v8'
 };