Add custom Template class with tojavascript filter

folium/template.py

@@ -0,0 +1,51 @@
+import json
+from typing import Union
+
+import jinja2
+from branca.element import Element
+
+from folium.utilities import JsCode, TypeJsonValue, camelize
+
+
+def tojavascript(obj: Union[str, JsCode, dict, list, Element]) -> str:
+    if isinstance(obj, JsCode):
+        return obj.js_code
+    elif isinstance(obj, Element):
+        return obj.get_name()
+    elif isinstance(obj, dict):
+        out = ["{\n"]
+        for key, value in obj.items():
+            out.append(f'  "{camelize(key)}": ')
+            out.append(tojavascript(value))
+            out.append(",\n")
+        out.append("}")
+        return "".join(out)
+    elif isinstance(obj, list):
+        out = ["[\n"]
+        for value in obj:
+            out.append(tojavascript(value))
+            out.append(",\n")
+        out.append("]")
+        return "".join(out)
+    else:
+        return _to_escaped_json(obj)
+
+
+def _to_escaped_json(obj: TypeJsonValue) -> str:
+    return (
+        json.dumps(obj)
+        .replace("<", "\\u003c")
+        .replace(">", "\\u003e")
+        .replace("&", "\\u0026")
+        .replace("'", "\\u0027")
+    )
+
+
+class Environment(jinja2.Environment):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.filters["tojavascript"] = tojavascript
+
+
+class Template(jinja2.Template):
+    environment_class = Environment

tests/test_template.py

@@ -0,0 +1,68 @@
+from branca.element import Element
+
+from folium import JsCode
+from folium.template import Environment, Template, _to_escaped_json, tojavascript
+
+
+def test_tojavascript_with_jscode():
+    js_code = JsCode("console.log('Hello, World!')")
+    assert tojavascript(js_code) == "console.log('Hello, World!')"
+
+
+def test_tojavascript_with_element():
+    element = Element()
+    assert tojavascript(element) == element.get_name()
+
+
+def test_tojavascript_with_dict():
+    dict_obj = {"key": "value"}
+    assert tojavascript(dict_obj) == '{\n  "key": "value",\n}'
+
+
+def test_tojavascript_with_list():
+    list_obj = ["value1", "value2"]
+    assert tojavascript(list_obj) == '[\n"value1",\n"value2",\n]'
+
+
+def test_tojavascript_with_string():
+    assert tojavascript("Hello, World!") == _to_escaped_json("Hello, World!")
+
+
+def test_tojavascript_with_combined_elements():
+    js_code = JsCode("console.log('Hello, World!')")
+    element = Element()
+    combined_dict = {
+        "key": "value",
+        "list": ["value1", "value2", element, js_code],
+        "nested_dict": {"nested_key": "nested_value"},
+    }
+    result = tojavascript(combined_dict)
+    expected_lines = [
+        "{",
+        '  "key": "value",',
+        '  "list": [',
+        '"value1",',
+        '"value2",',
+        element.get_name() + ",",
+        "console.log('Hello, World!'),",
+        "],",
+        '  "nestedDict": {',
+        '  "nestedKey": "nested_value",',
+        "},",
+        "}",
+    ]
+    for result_line, expected_line in zip(result.splitlines(), expected_lines):
+        assert result_line == expected_line
+
+
+def test_to_escaped_json():
+    assert _to_escaped_json("hi<>&'") == '"hi\\u003c\\u003e\\u0026\\u0027"'
+
+
+def test_environment_filter():
+    env = Environment()
+    assert "tojavascript" in env.filters
+
+
+def test_template_environment_class():
+    assert Template.environment_class == Environment