Use JSON.parse method

<script>
    var bgjson = {{BgDict|tojson|safe}};
    console.log(jQuery.type(bgjson));
    console.log(JSON.parse(bgjson)[4]);
</script>

Python and javascript both have different ideas about how to represent a dictionary, which means that you need a intermediate representation in order to pass data between them. The most common way to do this is JSON, which is a simple lightweight data-interchange format.

Use the python json library to convert (or dump) your python dict into a JSON string. Then in the javascript parse the JSON string into a javascript dict. (If you are using JQuery, then use jQuery.parseJSON)

In Python:

import json
send_to_js = json.dumps({
 "name": "Paul",
 "age": "20",
 "gender": "male"
})

Then in JavaScript:

JSON.parse(send_to_js)
// result is {name: 'Paul', age: '20', gender: 'male'}

@Rubik, I may guess, alert() takes a string as parameter and you're passing it an object in second call to alert().

JSON.parse() creates an object from the string representation of any object (array, set etc.).

Please try to change your JS code as follows (just modify 2 lines):

Please comment if it doesn't work, I will update my answer to help you.

$(".dict").click(function () {
  alert("first alert");
  // var result = JSON.parse(jsonheaderdict);
  alert(JSON.stringify(jsonheaderdict));
});

» Try below sample code for verification.

var jsonheaderdict = {"F 1": ["BBBB", "AAAAA"], "F 2": ["ASDASD"], "F 3": ["QWEQWE"]};

console.log(jsonheaderdict); 

alert(jsonheaderdict)

alert(JSON.stringify(jsonheaderdict))

If you know all your keys are valid tokens you can use this simple code:

Copyimport json

def js_list(encoder, data):
    pairs = []
    for v in data:
        pairs.append(js_val(encoder, v))
    return "[" + ", ".join(pairs) + "]"

def js_dict(encoder, data):
    pairs = []
    for k, v in data.iteritems():
        pairs.append(k + ": " + js_val(encoder, v))
    return "{" + ", ".join(pairs) + "}"

def js_val(encoder, data):
    if isinstance(data, dict):
        val = js_dict(encoder, data)
    elif isinstance(data, list):
        val = js_list(encoder, data)
    else:
        val = encoder.encode(data)
    return val

encoder = json.JSONEncoder(ensure_ascii=False)
js_val(encoder, {'height': 100, 'title': 'some great title'})

The return value of js_val() is in your desired format.

Remove export default when reading the file, and add it back when writing.

with open("abc.js") as f:
    contents = f.read()

contents = contents.replace('export default', '')
data = json.loads(contents)
data['Country'] = 'Italy'
new_contents = 'export default' + json.dumps(data)

with open("abc.js", "w") as f:
    f.write(new_contents)

This should work:

var groups = JSON.parse('{{ groups|safe }}');

demjson.decode()

import demjson

# from
js_obj = '{x:1, y:2, z:3}'

# to
py_obj = demjson.decode(js_obj)

chompjs.parse_js_object()

import chompjs

# from
js_obj = '{x:1, y:2, z:3}'

# to
py_obj = chompjs.parse_js_object(js_obj)

jsonnet.evaluate_snippet()

import json, _jsonnet

# from
js_obj = '{x:1, y:2, z:3}'

# to
py_obj = json.loads(_jsonnet.evaluate_snippet('snippet', js_obj))

ast.literal_eval()

import ast

# from
js_obj = "{'x':1, 'y':2, 'z':3}"

# to
py_obj = ast.literal_eval(js_obj)