​
default

Allows you to specify a fallback in case a value doesn’t exist. default will show its value if the left side is falsy or empty (string or Array). In this example, product_price is not defined, so the default value is used. 
{{ product_price | default: 2.99 }}

2.99
In this example, product_price is defined, so the default value is not used. 
{% assign product_price = 4.99 %}
{{ product_price | default: 2.99 }}

4.99
In this example, product_price is empty, so the default value is used. 
{% assign product_price = "" %}
{{ product_price | default: 2.99 }}

2.99

​
Allowing false

To allow variables to return false instead of the default value, you can use the allow_false parameter. 
{% assign display_price = false %}
{{ display_price | default: true, allow_false: true }}

false

​
json

Convert values to string via JSON.stringify(), for debug purpose. 
{% assign arr = "foo bar coo" | split: " " %}
{{ arr | json }}

["foo","bar","coo"]

​
parse_json

Convert a string value to a valid JSON object. If the value is not a valid JSON, the returned value will be nil. 
{% assign obj = '{"foo": "bar"}' | parse_json %}
{% assign arr = '["Hi", "there"]' | parse_json %}
{% assign invalid = '{"foo" = "bar"}' | parse_json %}
{{ obj.foo }}
{{ arr[1]}}
{{ invalid }}

bar
there

​
Space

An additional space parameter can be specified to format the JSON. 
{% assign arr = "foo bar coo" | split: " " %}
{{ arr | json: 4 }}

[
    "foo",
    "bar",
    "coo"
]

​
jsonify

See json.

​
inspect

Similar with json, but inspect allows cyclic structure. For the scope below: 
const foo = {
    bar: 'BAR'
}
foo.foo = foo
const scope = { foo }

{% foo | inspect %}

{"bar":"BAR","foo":"[Circular]"}

​
Formatting

An additional space argument can be specified for the indent width. 
{{ foo | inspect: 4 }}

{
    "bar": "BAR",
    "foo": "[Circular]"
}

​
to_integer

Convert values to number. 
{{ "123" | to_integer | json }}

123