diff --git a/Cargo.lock b/Cargo.lock
index 55b7bb9d55e..08fd3a98c01 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -17,7 +17,7 @@ dependencies = [
  "num-traits",
  "once_cell",
  "rand",
- "regex",
+ "regress",
  "rustc-hash",
  "ryu-js",
  "serde",
@@ -971,6 +971,15 @@ version = "0.6.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "26412eb97c6b088a6997e05f69403a802a92d520de2f8e63c2b65f9e0f47c4e8"
 
+[[package]]
+name = "regress"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d669f9db16c334d72d7f92d52874373eb0df8f642230401952a6901872fee4c5"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "rust-argon2"
 version = "0.8.2"
diff --git a/boa/Cargo.toml b/boa/Cargo.toml
index 2d7247bf760..7c2beb3c12d 100644
--- a/boa/Cargo.toml
+++ b/boa/Cargo.toml
@@ -18,7 +18,7 @@ gc = { version = "0.3.6", features = ["derive"] }
 serde_json = "1.0.58"
 rand = "0.7.3"
 num-traits = "0.2.12"
-regex = "1.3.9"
+regress = "0.1.4"
 rustc-hash = "1.1.0"
 num-bigint = { version = "0.3.0", features = ["serde"] }
 num-integer = "0.1.43"
diff --git a/boa/src/builtins/regexp/mod.rs b/boa/src/builtins/regexp/mod.rs
index 327c0997aea..12f78fbc9f8 100644
--- a/boa/src/builtins/regexp/mod.rs
+++ b/boa/src/builtins/regexp/mod.rs
@@ -17,7 +17,7 @@ use crate::{
     value::{RcString, Value},
     BoaProfiler, Context, Result,
 };
-use regex::Regex;
+use regress::{Flags, Regex};
 
 #[cfg(test)]
 mod tests;
@@ -123,7 +123,6 @@ impl RegExp {
 
         // parse flags
         let mut sorted_flags = String::new();
-        let mut pattern = String::new();
         let mut dot_all = false;
         let mut global = false;
         let mut ignore_case = false;
@@ -137,34 +136,26 @@ impl RegExp {
         if regex_flags.contains('i') {
             ignore_case = true;
             sorted_flags.push('i');
-            pattern.push('i');
         }
         if regex_flags.contains('m') {
             multiline = true;
             sorted_flags.push('m');
-            pattern.push('m');
         }
         if regex_flags.contains('s') {
             dot_all = true;
             sorted_flags.push('s');
-            pattern.push('s');
         }
         if regex_flags.contains('u') {
             unicode = true;
             sorted_flags.push('u');
-            //pattern.push('s'); // rust uses utf-8 anyway
         }
         if regex_flags.contains('y') {
             sticky = true;
             sorted_flags.push('y');
         }
-        // the `regex` crate uses '(?{flags})` inside the pattern to enable flags
-        if !pattern.is_empty() {
-            pattern = format!("(?{})", pattern);
-        }
-        pattern.push_str(regex_body.as_str());
 
-        let matcher = Regex::new(pattern.as_str()).expect("failed to create matcher");
+        let matcher = Regex::newf(regex_body.as_str(), Flags::from(sorted_flags.as_str()))
+            .expect("failed to create matcher");
         let regexp = RegExp {
             matcher,
             use_last_index: global || sticky,
@@ -319,17 +310,18 @@ impl RegExp {
         let mut last_index = this.get_field("lastIndex").to_index(ctx)?;
         let result = if let Some(object) = this.as_object() {
             let regex = object.as_regexp().unwrap();
-            let result = if let Some(m) = regex.matcher.find_at(arg_str.as_str(), last_index) {
-                if regex.use_last_index {
-                    last_index = m.end();
-                }
-                true
-            } else {
-                if regex.use_last_index {
-                    last_index = 0;
-                }
-                false
-            };
+            let result =
+                if let Some(m) = regex.matcher.find_from(arg_str.as_str(), last_index).next() {
+                    if regex.use_last_index {
+                        last_index = m.total().end;
+                    }
+                    true
+                } else {
+                    if regex.use_last_index {
+                        last_index = 0;
+                    }
+                    false
+                };
             Ok(Value::boolean(result))
         } else {
             panic!("object is not a regexp")
@@ -358,35 +350,36 @@ impl RegExp {
         let mut last_index = this.get_field("lastIndex").to_index(ctx)?;
         let result = if let Some(object) = this.as_object() {
             let regex = object.as_regexp().unwrap();
-            let mut locations = regex.matcher.capture_locations();
-            let result = if let Some(m) =
-                regex
-                    .matcher
-                    .captures_read_at(&mut locations, arg_str.as_str(), last_index)
-            {
-                if regex.use_last_index {
-                    last_index = m.end();
-                }
-                let mut result = Vec::with_capacity(locations.len());
-                for i in 0..locations.len() {
-                    if let Some((start, end)) = locations.get(i) {
-                        result.push(Value::from(
-                            arg_str.get(start..end).expect("Could not get slice"),
-                        ));
-                    } else {
-                        result.push(Value::undefined());
+            let result = {
+                if let Some(m) = regex.matcher.find_from(arg_str.as_str(), last_index).next() {
+                    if regex.use_last_index {
+                        last_index = m.total().end;
+                    }
+                    let groups = m.captures.len() + 1;
+                    let mut result = Vec::with_capacity(groups);
+                    for i in 0..groups {
+                        if let Some(range) = m.group(i) {
+                            result.push(Value::from(
+                                arg_str.get(range).expect("Could not get slice"),
+                            ));
+                        } else {
+                            result.push(Value::undefined());
+                        }
                     }
-                }
 
-                let result = Value::from(result);
-                result.set_property("index", Property::default().value(Value::from(m.start())));
-                result.set_property("input", Property::default().value(Value::from(arg_str)));
-                result
-            } else {
-                if regex.use_last_index {
-                    last_index = 0;
+                    let result = Value::from(result);
+                    result.set_property(
+                        "index",
+                        Property::default().value(Value::from(m.total().start)),
+                    );
+                    result.set_property("input", Property::default().value(Value::from(arg_str)));
+                    result
+                } else {
+                    if regex.use_last_index {
+                        last_index = 0;
+                    }
+                    Value::null()
                 }
-                Value::null()
             };
             Ok(result)
         } else {
@@ -416,7 +409,7 @@ impl RegExp {
         if flags.contains('g') {
             let mut matches = Vec::new();
             for mat in matcher.find_iter(&arg) {
-                matches.push(Value::from(mat.as_str()));
+                matches.push(Value::from(&arg[mat.total()]));
             }
             if matches.is_empty() {
                 return Ok(Value::null());
@@ -464,29 +457,29 @@ impl RegExp {
             let regex = object.as_regexp().unwrap();
             let mut matches = Vec::new();
 
-            for m in regex.matcher.find_iter(&arg_str) {
-                if let Some(caps) = regex.matcher.captures(&m.as_str()) {
-                    let match_vec = caps
-                        .iter()
-                        .map(|group| match group {
-                            Some(g) => Value::from(g.as_str()),
-                            None => Value::undefined(),
-                        })
-                        .collect::<Vec<Value>>();
-
-                    let match_val = Value::from(match_vec);
-
-                    match_val
-                        .set_property("index", Property::default().value(Value::from(m.start())));
-                    match_val.set_property(
-                        "input",
-                        Property::default().value(Value::from(arg_str.clone())),
-                    );
-                    matches.push(match_val);
-
-                    if !regex.flags.contains('g') {
-                        break;
-                    }
+            for mat in regex.matcher.find_iter(&arg_str) {
+                let match_vec: Vec<Value> = mat
+                    .groups()
+                    .map(|group| match group {
+                        Some(range) => Value::from(&arg_str[range]),
+                        None => Value::undefined(),
+                    })
+                    .collect();
+
+                let match_val = Value::from(match_vec);
+
+                match_val.set_property(
+                    "index",
+                    Property::default().value(Value::from(mat.total().start)),
+                );
+                match_val.set_property(
+                    "input",
+                    Property::default().value(Value::from(arg_str.clone())),
+                );
+                matches.push(match_val);
+
+                if !regex.flags.contains('g') {
+                    break;
                 }
             }
 
diff --git a/boa/src/builtins/string/mod.rs b/boa/src/builtins/string/mod.rs
index a1a76c12b9b..ac65d5b7cf8 100644
--- a/boa/src/builtins/string/mod.rs
+++ b/boa/src/builtins/string/mod.rs
@@ -20,7 +20,7 @@ use crate::{
     value::{RcString, Value},
     BoaProfiler, Context, Result,
 };
-use regex::Regex;
+use regress::Regex;
 use std::{
     char::decode_utf16,
     cmp::{max, min},
@@ -554,8 +554,9 @@ impl String {
             None => return Ok(Value::from(primitive_val)),
         };
         let caps = re
-            .captures(&primitive_val)
-            .expect("unable to get capture groups from text");
+            .find(&primitive_val)
+            .expect("unable to get capture groups from text")
+            .captures;
 
         let replace_value = if args.len() > 1 {
             // replace_object could be a string or function or not exist at all
@@ -583,17 +584,16 @@ impl String {
                                 }
                                 (Some('&'), _) => {
                                     // $&
-                                    let matched = caps.get(0).expect("cannot get matched value");
-                                    result.push_str(matched.as_str());
+                                    result.push_str(&primitive_val[mat.total()]);
                                 }
                                 (Some('`'), _) => {
                                     // $`
-                                    let start_of_match = mat.start();
+                                    let start_of_match = mat.total().start;
                                     result.push_str(&primitive_val[..start_of_match]);
                                 }
                                 (Some('\''), _) => {
                                     // $'
-                                    let end_of_match = mat.end();
+                                    let end_of_match = mat.total().end;
                                     result.push_str(&primitive_val[end_of_match..]);
                                 }
                                 (Some(second), Some(third))
@@ -610,9 +610,9 @@ impl String {
                                             result.push(ch);
                                         }
                                     } else {
-                                        let group = match caps.get(nn) {
-                                            Some(text) => text.as_str(),
-                                            None => "",
+                                        let group = match mat.group(nn) {
+                                            Some(range) => &primitive_val[range.clone()],
+                                            _ => "",
                                         };
                                         result.push_str(group);
                                         chars.next(); // consume third
@@ -625,9 +625,9 @@ impl String {
                                         result.push(first);
                                         result.push(second);
                                     } else {
-                                        let group = match caps.get(n) {
-                                            Some(text) => text.as_str(),
-                                            None => "",
+                                        let group = match mat.group(n) {
+                                            Some(range) => &primitive_val[range.clone()],
+                                            _ => "",
                                         };
                                         result.push_str(group);
                                     }
@@ -654,16 +654,16 @@ impl String {
                 }
                 Value::Object(_) => {
                     // This will return the matched substring first, then captured parenthesized groups later
-                    let mut results: Vec<Value> = caps
-                        .iter()
-                        .map(|capture| Value::from(capture.unwrap().as_str()))
+                    let mut results: Vec<Value> = mat
+                        .groups()
+                        .map(|group| match group {
+                            Some(range) => Value::from(&primitive_val[range]),
+                            None => Value::undefined(),
+                        })
                         .collect();
 
                     // Returns the starting byte offset of the match
-                    let start = caps
-                        .get(0)
-                        .expect("Unable to get Byte offset from string for match")
-                        .start();
+                    let start = mat.total().start;
                     results.push(Value::from(start));
                     // Push the whole string being examined
                     results.push(Value::from(primitive_val.to_string()));
@@ -679,7 +679,7 @@ impl String {
         };
 
         Ok(Value::from(primitive_val.replacen(
-            &mat.as_str(),
+            &primitive_val[mat.total()],
             &replace_value,
             1,
         )))
diff --git a/boa/src/builtins/string/tests.rs b/boa/src/builtins/string/tests.rs
index 68ef1439c25..af0eeb0d32f 100644
--- a/boa/src/builtins/string/tests.rs
+++ b/boa/src/builtins/string/tests.rs
@@ -10,7 +10,7 @@ fn length() {
     const a = new String(' ');
     const b = new String('\ud834\udf06');
     const c = new String(' \b ');
-    cosnt d = new String('中文长度')
+    const d = new String('中文长度')
     "#;
     eprintln!("{}", forward(&mut engine, init));
     let a = forward(&mut engine, "a.length");
@@ -275,11 +275,12 @@ fn replace_with_function() {
     let mut engine = Context::new();
     let init = r#"
         var a = "ecmascript is cool";
-        var p1, p2, p3;
-        var replacer = (match, cap1, cap2, cap3) => {
+        var p1, p2, p3, length;
+        var replacer = (match, cap1, cap2, cap3, len) => {
             p1 = cap1;
             p2 = cap2;
             p3 = cap3;
+            length = len;
             return "awesome!";
         };
 
@@ -294,6 +295,7 @@ fn replace_with_function() {
     assert_eq!(forward(&mut engine, "p1"), "\"o\"");
     assert_eq!(forward(&mut engine, "p2"), "\"o\"");
     assert_eq!(forward(&mut engine, "p3"), "\"l\"");
+    assert_eq!(forward(&mut engine, "length"), "14");
 }
 
 #[test]