Javascript - How to filter tree-like named object?

Drun555
August 31, 2023
191 views
1 vote
2 Answers

I have a tree object like below, and I need to search through it. I know there’s already some answers on topics like this here, but they are, unfortunately, do not comply with my structure.

const tree = {
    "28": {
        "label": "lorem"
        "children": {
            "188": {
                "label": "ipsum"
                "children": {
                    "482": {
                        "label": "fish"
                        "children": {
                            "185": {
                                "label": "dog"
                            },
                            "289": {
                                "label": "cat"
                            }
                        }
                    }
                }
            }
        }
    },
    "33": {
        "label": "water"
        "children": {
            "95": {
                "label": "fire"
                "children": {
                    "181": {
                        "label": "gas"
                        "children": {
                            "100": {
                                "label": "station"
                            }
                        }
                    }
                    "182": {
                        "label": ""
                        "children": {
                            "100": {
                                "label": "sushi"
                            }
                        }
                    }
                }
            }
        }
    }
}

For example, if I’ll search for ‘fish’, output should be like this:

{
    "28": {
        "label": "lorem"
        "children": {
            "188": {
                "label": "ipsum"
                "children": {
                    "482": {
                        "label": "fish"
                        "children": {
                            "185": {
                                "label": "dog"
                            },
                            "289": {
                                "label": "cat"
                            }
                        }
                    }
                }
            }
        }
    }
}

And if I’ll search for ‘dog’ instead:

{
    "28": {
        "label": "lorem"
        "children": {
            "188": {
                "label": "ipsum"
                "children": {
                    "482": {
                        "label": "fish"
                        "children": {
                            "185": {
                                "label": "dog"
                            }
                        }
                    }
                }
            }
        }
    }
}

I tried to use these gentlemen’s answers, but couldn’t adapt them to named objects:

How to filter a tree structure while keeping the decendants of the parents that are filtered out?

A Javascript function to filter tree structured json with a search term. exclude any object which donot match the search term

Answers

To search through the tree structure and preserve its hierarchy, you can use a recursive function that:

Checks if the current node’s label matches the search term.
If not, it then checks its children.
If a child matches the search term or any of its descendants match the term, it retains that child and continues searching deeper

Here is an example of a solution:

function filterTree(inputTree, searchTerm) {
    let resultTree = {};

    for (let key in inputTree) {
        let node = inputTree[key];
        
        // If the current label matches, it will return the entire subtree
        if (node.label === searchTerm) {
            resultTree[key] = node;
        } else {
            // Otherwise it will check the children
            let childrenResult = node.children ? filterTree(node.children, searchTerm) : {};

            // If any children matched, it will include this node in the result
            // but only with those children that matched
            if (Object.keys(childrenResult).length) {
                resultTree[key] = { ...node, children: childrenResult };
            }
        }
    }

    return resultTree;
}


// Example of a usage
const searchTerm = 'fish';
const result = filterTree(tree, searchTerm);
console.log(result);

You can replace the searchTerm with ‘dog’ or any other creature you like and it should work.

Use a recursive function that searches in the children property recursively.
Note that we don’t use here spread syntax and functional approach since it would be slower.

const search = (obj, str) => {

  for(const key in obj){
    const item = obj[key];

    if(item.label === str){
      return {[key]: item };
    }
    if(item.children){
      const found = search(item.children, str);
      if(found){
        return {[key]: Object.assign({}, item, {children: found})};
      }
    }
  }
  return null;
};

['fish', 'dog', 'dummy'].forEach(str => console.log(str, search(tree, str)));

<script>
const tree = {
    "28": {
        "label": "lorem",
        "children": {
            "188": {
                "label": "ipsum",
                "children": {
                    "482": {
                        "label": "fish",
                        "children": {
                            "185": {
                                "label": "dog"
                            },
                            "289": {
                                "label": "cat"
                            }
                        }
                    }
                }
            }
        }
    },
    "33": {
        "label": "water",
        "children": {
            "95": {
                "label": "fire",
                "children": {
                    "181": {
                        "label": "gas",
                        "children": {
                            "100": {
                                "label": "station"
                            }
                        }
                    },
                    "182": {
                        "label": "",
                        "children": {
                            "100": {
                                "label": "sushi"
                            }
                        }
                    }
                }
            }
        }
    }
}
</script>

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Javascript – How to filter tree-like named object?

Answers