Deep clone in JavaScript

Copies a nested structure so that changing the copy leaves the original alone.

function deepClone(value) {
  if (value === null || typeof value !== "object") return value;
  if (Array.isArray(value)) return value.map(deepClone);
  const out = {};
  for (const key of Object.keys(value)) {
    out[key] = deepClone(value[key]);
  }
  return out;
}

Keywords and builtins used here

• Array
• Object
• const
• for
• function
• if
• of
• return

The run, in numbers

Lines

9

Characters to type

251

Tokens

74

Three-star pace

95 tpm

At the three-star pace of 95 tokens a minute, this run takes about 47 seconds.

Type this snippet

Step 8 of 8 in Objects & collections, step 34 of 43 in Language basics.

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