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(source: unknown, target: unknown) => string;
The diff utility makes it easier to provide a helpful suggestion for check messages. We use the jest-diff utility to generate a diff that highlights values present in target but not source. Values will be stringified and parsed as lines of text. Lines that appear in target but not source will appear in red with a + prefix.

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Parameters

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source
unknown
required
Any value, representing the source of the diff.
​
target
unknown
required
Any value, representing the target of the diff.

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Returns

Returns a string representing the diff between source and target.

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Example

diff('first', 'second');
//   first
// + second

diff(
  { name: 'my-package', version: '1.0.0' },
  { name: 'my-package', version: '2.0.0' },
);
//   Object {
//     "name": "my-package",
//     "version": "1.0.0",
// +   "version": "2.0.0",
//   }