/**
 * From Emscripten project
 */
/**
 * Returns the number of bytes the given Javascript string takes if encoded as a
 * UTF8 byte array, EXCLUDING the null terminator byte.
 *
 * @param {string} str - JavaScript string to operator on
 * @return {number} Length, in bytes, of the UTF8 encoded string.
 */
export declare function lengthBytesUTF8(str: string): number;
/**
 * Copies the given Javascript String object 'str' to the given byte array at
 * address 'outIdx', encoded in UTF8 form and null-terminated. The copy will
 * require at most str.length*4+1 bytes of space in the HEAP.  Use the function
 * lengthBytesUTF8 to compute the exact number of bytes (excluding null
 * terminator) that this function will write.
 *
 * @param {string} str - The Javascript string to copy.
 * @param {ArrayBufferView|Array<number>} heap - The array to copy to. Each
 *                                               index in this array is assumed
 *                                               to be one 8-byte element.
 * @param {number} outIdx - The starting offset in the array to begin the copying.
 * @param {number} maxBytesToWrite - The maximum number of bytes this function
 *                                   can write to the array.  This count should
 *                                   include the null terminator, i.e. if
 *                                   maxBytesToWrite=1, only the null terminator
 *                                   will be written and nothing else.
 *                                   maxBytesToWrite=0 does not write any bytes
 *                                   to the output, not even the null
 *                                   terminator.
 * @return {number} The number of bytes written, EXCLUDING the null terminator.
 */
export declare function stringToUTF8(str: string, heap: Uint8Array, outIdx: number, maxBytesToWrite: number): number;