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startsWith

Instance method on String.prototype.

Returns true if the sequence of elements of searchString converted to a String is the same as the corresponding elements of this object (converted to a String) starting at position. Otherwise returns false.

startsWith(input: { string: <receiver>; searchString: string; position?: number; prompt?: string }): Promise<boolean>

The prompt field is optional. When omitted (or set to an empty string) the wrapper falls back to the native String.prototype.startsWith and returns a resolved Promise without contacting the LLM. When present, the LLM is given the original arguments plus your prompt and is asked to behave like the original method.

import { configureClient, neuro } from 'neuro-ts';
configureClient({ apiKey: process.env.OPENAI_API_KEY });
// Prefix check at position; the default-zero is the bug we keep almost reporting.
await neuro.string.startsWith({ string: header, searchString: 'Bearer ', position: 0, prompt: 'return true if the string starts with searchString at position, defaulting position to 0 even though we keep wishing it defaulted to "the boundary the parser is at"' });

The exact system prompt the SDK sends to your model when you provide a prompt field:

Generated promptString.prototype.startsWith
You are simulating the JavaScript built-in `String.prototype.startsWith`.
## Original signature(s)
  Overload 1: (searchString: string, position?: number) => boolean
## JSDoc
Returns true if the sequence of elements of searchString converted to a String is the
same as the corresponding elements of this object (converted to a String) starting at
position. Otherwise returns false.

## How to respond
- Behave EXACTLY as the original `startsWith` would, but use the user's intent to choose any callback / comparator / transform logic that the original would normally accept as an argument.
- Strictly preserve the original return type and shape.
- Output ONLY the JSON-encoded return value of the function call.
- Do NOT include explanations, prose, comments, or markdown fences.
- If the function would return `undefined`, output the literal string `undefined`.
- For Date / RegExp / Map / Set / TypedArray returns, output an object of the form { "__type": "Date" | "RegExp" | "Map" | "Set" | "<TypedArrayName>", ... } so the SDK can rehydrate it.