Flatten JavaScript Object with Recursion

Introduction

In this lab, we will explore a JavaScript function that flattens an object with the paths for keys. The function uses recursion and Object.keys() combined with Array.prototype.reduce() to convert every leaf node to a flattened path node. By the end of this lab, you will have a better understanding of how to manipulate JavaScript objects and flatten them for easier data processing.

Skills Graph

%%%%{init: {'theme':'neutral'}}%%%% flowchart RL javascript(("`JavaScript`")) -.-> javascript/BasicConceptsGroup(["`Basic Concepts`"]) javascript(("`JavaScript`")) -.-> javascript/AdvancedConceptsGroup(["`Advanced Concepts`"]) javascript/BasicConceptsGroup -.-> javascript/variables("`Variables`") javascript/BasicConceptsGroup -.-> javascript/data_types("`Data Types`") javascript/BasicConceptsGroup -.-> javascript/arith_ops("`Arithmetic Operators`") javascript/BasicConceptsGroup -.-> javascript/comp_ops("`Comparison Operators`") javascript/BasicConceptsGroup -.-> javascript/cond_stmts("`Conditional Statements`") javascript/BasicConceptsGroup -.-> javascript/array_methods("`Array Methods`") javascript/AdvancedConceptsGroup -.-> javascript/higher_funcs("`Higher-Order Functions`") javascript/AdvancedConceptsGroup -.-> javascript/destr_assign("`Destructuring Assignment`") javascript/AdvancedConceptsGroup -.-> javascript/template_lit("`Template Literals`") subgraph Lab Skills javascript/variables -.-> lab-28312{{"`Flatten JavaScript Object with Recursion`"}} javascript/data_types -.-> lab-28312{{"`Flatten JavaScript Object with Recursion`"}} javascript/arith_ops -.-> lab-28312{{"`Flatten JavaScript Object with Recursion`"}} javascript/comp_ops -.-> lab-28312{{"`Flatten JavaScript Object with Recursion`"}} javascript/cond_stmts -.-> lab-28312{{"`Flatten JavaScript Object with Recursion`"}} javascript/array_methods -.-> lab-28312{{"`Flatten JavaScript Object with Recursion`"}} javascript/higher_funcs -.-> lab-28312{{"`Flatten JavaScript Object with Recursion`"}} javascript/destr_assign -.-> lab-28312{{"`Flatten JavaScript Object with Recursion`"}} javascript/template_lit -.-> lab-28312{{"`Flatten JavaScript Object with Recursion`"}} end

Flattening an Object

To flatten an object with paths for keys, follow these steps:

Open the Terminal/SSH and type node to start practicing coding.
Use recursion to flatten the object.
Use Object.keys() combined with Array.prototype.reduce() to convert every leaf node to a flattened path node.
If the value of a key is an object, call the function recursively with the appropriate prefix to create the path using Object.assign().
Otherwise, add the appropriate prefixed key-value pair to the accumulator object.
Omit the second argument, prefix, unless you want every key to have a prefix.

Here is an example implementation:

const flattenObject = (obj, prefix = "") =>
  Object.keys(obj).reduce((acc, k) => {
    const pre = prefix.length ? `${prefix}.` : "";
    if (
      typeof obj[k] === "object" &&
      obj[k] !== null &&
      Object.keys(obj[k]).length > 0
    ) {
      Object.assign(acc, flattenObject(obj[k], pre + k));
    } else {
      acc[pre + k] = obj[k];
    }
    return acc;
  }, {});

You can use the flattenObject function like this:

flattenObject({ a: { b: { c: 1 } }, d: 1 }); // { 'a.b.c': 1, d: 1 }

Summary

Congratulations! You have completed the Flatten Object lab. You can practice more labs in LabEx to improve your skills.

Flatten JavaScript Object with Recursion

Introduction

Skills Graph

Flattening an Object

Summary

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