diff --git a/assets/highlighting-tests/javascript.js b/assets/highlighting-tests/javascript.js
new file mode 100644
index 00000000000..53c000b1f2b
--- /dev/null
+++ b/assets/highlighting-tests/javascript.js
@@ -0,0 +1,59 @@
+// Single-line comment
+/* Multi-line
+   comment */
+
+const single = 'single quoted string';
+const double = "double quoted string";
+const template = `template string with ${single}`;
+
+const decimal = 42;
+const negative = -3.14e+2;
+const hex = 0x2a;
+const binary = 0b101010;
+const octal = 0o52;
+
+const truthy = true;
+const falsy = false;
+const empty = null;
+const missing = undefined;
+const notANumber = NaN;
+const infinite = Infinity;
+
+export async function greet(name) {
+  if (name instanceof String) {
+    return;
+  } else if (name in { user: "ok" }) {
+    throw new Error("unexpected");
+  }
+
+  for (let i = 0; i < 3; i++) {
+    while (false) {
+      break;
+    }
+  }
+
+  try {
+    return console.log(template, name);
+  } catch (error) {
+    return void error;
+  } finally {
+    delete globalThis.temp;
+  }
+}
+
+class Person extends Object {
+  constructor(name) {
+    super();
+    this.name = name;
+  }
+}
+
+const result = greet("world");
+switch (result) {
+  case true:
+    break;
+  default:
+    continueLabel: do {
+      break continueLabel;
+    } while (false);
+}
diff --git a/assets/highlighting-tests/markdown.md b/assets/highlighting-tests/markdown.md
index c4845eb6801..555b182f961 100644
--- a/assets/highlighting-tests/markdown.md
+++ b/assets/highlighting-tests/markdown.md
@@ -66,6 +66,12 @@ Reference: ![Logo][logo-ref]
 echo "Hello, world" | tr a-z A-Z
 ```
 
+```javascript
+export function greet(name) {
+  return `hello ${name}`;
+}
+```
+
 ```json
 {
   "name": "gfm-kitchen-sink",
@@ -73,3 +79,8 @@ echo "Hello, world" | tr a-z A-Z
   "scripts": { "test": "echo ok" }
 }
 ```
+
+```python
+def greet(name: str) -> str:
+    return f"hello {name}"
+```
diff --git a/assets/highlighting-tests/python.py b/assets/highlighting-tests/python.py
new file mode 100644
index 00000000000..4c49bbd9a59
--- /dev/null
+++ b/assets/highlighting-tests/python.py
@@ -0,0 +1,48 @@
+# Single-line comment
+'''Triple single quoted string'''
+"""Triple double quoted string"""
+
+single = 'single quoted string'
+double = "double quoted string"
+
+decimal = 42
+negative = -3.14e+2
+hex_value = 0x2A
+binary_value = 0b101010
+octal_value = 0o52
+complex_value = 1.5j
+
+truthy = True
+falsy = False
+nothing = None
+
+@decorator
+async def greet(name: str) -> None:
+    value = f"Hello, {name}"
+
+    if value and name is not None:
+        print(value)
+    elif value in {"hello", "world"}:
+        raise ValueError("unexpected")
+    else:
+        return None
+
+    for item in [single, double]:
+        while False:
+            break
+
+    try:
+        assert item
+    except Exception as exc:
+        yield exc
+    finally:
+        pass
+
+
+class Person:
+    def __init__(self, name):
+        self.name = name
+
+
+result = greet("world")
+lambda_value = lambda x: x + 1
diff --git a/assets/highlighting-tests/zsh.sh b/assets/highlighting-tests/zsh.sh
new file mode 100644
index 00000000000..46ae4cf461a
--- /dev/null
+++ b/assets/highlighting-tests/zsh.sh
@@ -0,0 +1,40 @@
+#!/usr/bin/env zsh
+# zsh-style shell sample
+
+setopt autocd extendedglob
+
+typeset -g POWERLEVEL="lean"
+readonly ZSH_THEME="agnoster"
+
+plugins=(git docker fzf)
+
+alias ll='ls -lah'
+alias gs='git status'
+
+path=("$HOME/bin" $path)
+export EDITOR="nvim"
+
+function mkcd() {
+    local dir="$1"
+    mkdir -p "$dir" && cd "$dir"
+}
+
+if [[ -n "$HOME" ]]; then
+    echo "home is $HOME"
+elif [[ -z "$HOME" ]]; then
+    echo "missing home"
+else
+    echo "unexpected"
+fi
+
+for plugin in $plugins; do
+    echo "$plugin"
+done
+
+case "$ZSH_THEME" in
+    agnoster) echo "theme selected" ;;
+    *) echo "default theme" ;;
+esac
+
+source "$HOME/.zsh_aliases"
+mkcd "${HOME}/tmp"
diff --git a/crates/lsh/definitions/bash.lsh b/crates/lsh/definitions/bash.lsh
new file mode 100644
index 00000000000..433cb0f2ffd
--- /dev/null
+++ b/crates/lsh/definitions/bash.lsh
@@ -0,0 +1,61 @@
+#[display_name = "Bash"]
+#[path = "**/*.bash"]
+#[path = "**/*.sh"]
+#[path = "**/.bash_profile"]
+#[path = "**/.bashrc"]
+#[path = "**/.profile"]
+pub fn bash() {
+    until /$/ {
+        yield other;
+
+        if /#.*/ {
+            yield comment;
+        } else if /'/ {
+            until /$/ {
+                yield string;
+                if /'/ { yield string; break; }
+                await input;
+            }
+        } else if /"/ {
+            until /$/ {
+                yield string;
+                if /\\./ {}
+                else if /"/ { yield string; break; }
+                await input;
+            }
+        } else if /`/ {
+            until /$/ {
+                yield string;
+                if /\\./ {}
+                else if /`/ { yield string; break; }
+                await input;
+            }
+        } else if /\$\{[^}]+\}|\$[A-Za-z_]\w*|\$\d+|\$[#?*!@$-]/ {
+            yield variable;
+        } else if /(?:if|then|elif|else|fi|for|while|until|do|done|case|esac|in|select)\>/ {
+            if /\w+/ {
+                yield other;
+            } else {
+                yield keyword.control;
+            }
+        } else if /(?:declare|export|function|local|readonly|source)\>/ {
+            if /\w+/ {
+                yield other;
+            } else {
+                yield keyword.other;
+            }
+        } else if /-?(?:(?i:0x[\da-fA-F]+)|\d+\.?\d*|\.\d+)(?i:e[+-]?\d+)?/ {
+            if /\w+/ {
+                yield other;
+            } else {
+                yield constant.numeric;
+            }
+        } else if /([A-Za-z_][\w-]*)\s*\(/ {
+            yield $1 as method;
+        } else if /[A-Za-z_][\w-]*/ {
+            // Gobble any other tokens that should not be highlighted
+        }
+
+        yield other;
+    }
+}
diff --git a/crates/lsh/definitions/javascript.lsh b/crates/lsh/definitions/javascript.lsh
new file mode 100644
index 00000000000..8c496a2278e
--- /dev/null
+++ b/crates/lsh/definitions/javascript.lsh
@@ -0,0 +1,74 @@
+#[display_name = "JavaScript"]
+#[path = "**/*.cjs"]
+#[path = "**/*.js"]
+#[path = "**/*.jsx"]
+#[path = "**/*.mjs"]
+pub fn javascript() {
+    until /$/ {
+        yield other;
+
+        if /\/\/.*/ {
+            yield comment;
+        } else if /\/\*/ {
+            loop {
+                yield comment;
+                await input;
+                if /\*\// {
+                    yield comment;
+                    break;
+                }
+            }
+        } else if /'/ {
+            until /$/ {
+                yield string;
+                if /\\./ {}
+                else if /'/ { yield string; break; }
+                await input;
+            }
+        } else if /"/ {
+            until /$/ {
+                yield string;
+                if /\\./ {}
+                else if /"/ { yield string; break; }
+                await input;
+            }
+        } else if /`/ {
+            loop {
+                yield string;
+                if /\\./ {}
+                else if /`/ { yield string; break; }
+                await input;
+            }
+        } else if /(?:if|else|switch|case|default|for|while|do|break|continue|try|catch|finally|throw|return)\>/ {
+            if /\w+/ {
+                yield other;
+            } else {
+                yield keyword.control;
+            }
+        } else if /(?:async|await|class|const|delete|export|extends|function|import|in|instanceof|let|new|of|super|this|typeof|var|void|yield)\>/ {
+            if /\w+/ {
+                yield other;
+            } else {
+                yield keyword.other;
+            }
+        } else if /(?:true|false|null|undefined|NaN|Infinity)\>/ {
+            if /\w+/ {
+                yield other;
+            } else {
+                yield constant.language;
+            }
+        } else if /-?(?:(?i:0x[\da-fA-F]+)|(?i:0b[01]+)|(?i:0o[0-7]+)|\d+\.?\d*|\.\d+)(?i:e[+-]?\d+)?/ {
+            if /\w+/ {
+                yield other;
+            } else {
+                yield constant.numeric;
+            }
+        } else if /([A-Za-z_$][\w$]*)\s*\(/ {
+            yield $1 as method;
+        } else if /[A-Za-z_$][\w$]*/ {
+            // Gobble any other tokens that should not be highlighted
+        }
+
+        yield other;
+    }
+}
diff --git a/crates/lsh/definitions/markdown.lsh b/crates/lsh/definitions/markdown.lsh
index 3fcc7721a15..fdb43a2e770 100644
--- a/crates/lsh/definitions/markdown.lsh
+++ b/crates/lsh/definitions/markdown.lsh
@@ -18,7 +18,27 @@ pub fn markdown() {
         yield comment;
     } else if /```/ {
         // NOTE: These checks are sorted alphabetically.
-        if /(?i:diff)/ {
+        if /(?i:bash|sh|shell)/ {
+            loop {
+                await input;
+                if /\s*```/ {
+                    return;
+                } else {
+                    bash();
+                    if /.*/ {}
+                }
+            }
+        } else if /(?i:zsh)/ {
+            loop {
+                await input;
+                if /\s*```/ {
+                    return;
+                } else {
+                    zsh();
+                    if /.*/ {}
+                }
+            }
+        } else if /(?i:diff)/ {
             loop {
                 await input;
                 if /\s*```/ {
@@ -30,6 +50,16 @@ pub fn markdown() {
                     if /.*/ {}
                 }
             }
+        } else if /(?i:javascript|js|jsx|mjs|cjs)/ {
+            loop {
+                await input;
+                if /\s*```/ {
+                    return;
+                } else {
+                    javascript();
+                    if /.*/ {}
+                }
+            }
         } else if /(?i:json)/ {
             loop {
                 await input;
@@ -40,6 +70,16 @@ pub fn markdown() {
                     if /.*/ {}
                 }
             }
+        } else if /(?i:py|python)/ {
+            loop {
+                await input;
+                if /\s*```/ {
+                    return;
+                } else {
+                    python();
+                    if /.*/ {}
+                }
+            }
         } else if /(?i:yaml)/ {
             loop {
                 await input;
diff --git a/crates/lsh/definitions/python.lsh b/crates/lsh/definitions/python.lsh
new file mode 100644
index 00000000000..becaed7fb89
--- /dev/null
+++ b/crates/lsh/definitions/python.lsh
@@ -0,0 +1,71 @@
+#[display_name = "Python"]
+#[path = "**/*.py"]
+#[path = "**/*.pyi"]
+#[path = "**/*.pyw"]
+pub fn python() {
+    until /$/ {
+        yield other;
+
+        if /#.*/ {
+            yield comment;
+        } else if /'''/ {
+            loop {
+                yield string;
+                if /'''/ { yield string; break; }
+                await input;
+            }
+        } else if /"""/ {
+            loop {
+                yield string;
+                if /"""/ { yield string; break; }
+                await input;
+            }
+        } else if /'/ {
+            until /$/ {
+                yield string;
+                if /\\./ {}
+                else if /'/ { yield string; break; }
+                await input;
+            }
+        } else if /"/ {
+            until /$/ {
+                yield string;
+                if /\\./ {}
+                else if /"/ { yield string; break; }
+                await input;
+            }
+        } else if /(?:if|elif|else|for|while|try|except|finally|return|break|continue|raise|with|match|case|pass)\>/ {
+            if /\w+/ {
+                yield other;
+            } else {
+                yield keyword.control;
+            }
+        } else if /(?:and|as|assert|async|await|class|def|del|from|global|import|in|is|lambda|nonlocal|not|or|yield)\>/ {
+            if /\w+/ {
+                yield other;
+            } else {
+                yield keyword.other;
+            }
+        } else if /(?:True|False|None)\>/ {
+            if /\w+/ {
+                yield other;
+            } else {
+                yield constant.language;
+            }
+        } else if /-?(?:(?i:0x[\da-fA-F]+)|(?i:0b[01]+)|(?i:0o[0-7]+)|\d+\.?\d*|\.\d+)(?i:e[+-]?\d+)?(?i:j)?/ {
+            if /\w+/ {
+                yield other;
+            } else {
+                yield constant.numeric;
+            }
+        } else if /@[A-Za-z_]\w*/ {
+            yield markup.link;
+        } else if /([A-Za-z_]\w*)\s*\(/ {
+            yield $1 as method;
+        } else if /[A-Za-z_]\w*/ {
+            // Gobble any other tokens that should not be highlighted
+        }
+
+        yield other;
+    }
+}
diff --git a/crates/lsh/definitions/zsh.lsh b/crates/lsh/definitions/zsh.lsh
new file mode 100644
index 00000000000..f22a4fff245
--- /dev/null
+++ b/crates/lsh/definitions/zsh.lsh
@@ -0,0 +1,60 @@
+#[display_name = "Zsh"]
+#[path = "**/*.zsh"]
+#[path = "**/.zprofile"]
+#[path = "**/.zshenv"]
+#[path = "**/.zshrc"]
+pub fn zsh() {
+    until /$/ {
+        yield other;
+
+        if /#.*/ {
+            yield comment;
+        } else if /'/ {
+            until /$/ {
+                yield string;
+                if /'/ { yield string; break; }
+                await input;
+            }
+        } else if /"/ {
+            until /$/ {
+                yield string;
+                if /\\./ {}
+                else if /"/ { yield string; break; }
+                await input;
+            }
+        } else if /`/ {
+            until /$/ {
+                yield string;
+                if /\\./ {}
+                else if /`/ { yield string; break; }
+                await input;
+            }
+        } else if /\$\{[^}]+\}|\$[A-Za-z_]\w*|\$\d+|\$[#?*!@$-]/ {
+            yield variable;
+        } else if /(?:if|then|elif|else|fi|for|while|until|do|done|case|esac|in|select)\>/ {
+            if /\w+/ {
+                yield other;
+            } else {
+                yield keyword.control;
+            }
+        } else if /(?:alias|autoload|bindkey|compdef|declare|emulate|export|function|local|readonly|setopt|source|typeset|unalias|unsetopt|zmodload)\>/ {
+            if /\w+/ {
+                yield other;
+            } else {
+                yield keyword.other;
+            }
+        } else if /-?(?:(?i:0x[\da-fA-F]+)|\d+\.?\d*|\.\d+)(?i:e[+-]?\d+)?/ {
+            if /\w+/ {
+                yield other;
+            } else {
+                yield constant.numeric;
+            }
+        } else if /([A-Za-z_][\w-]*)\s*\(/ {
+            yield $1 as method;
+        } else if /[A-Za-z_][\w-]*/ {
+            // Gobble any other tokens that should not be highlighted
+        }
+
+        yield other;
+    }
+}