ECMAScript

https://tc39.es/ecma262/multipage/
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ECMAScript is a standard object-oriented programming language used for client-side web scripting and...
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### Infinite loop prevention example: /(a*)b\1+/.exec("baaaac")

Source: https://tc39.es/ecma262/multipage/text-processing.html

Another example of empty match prevention, returning ["b", ""].

```javascript
/(a*)b\1+/.exec("baaaac")
```

--------------------------------

### Array.prototype.fill ( value [ , start [ , end ] ] )

Source: https://tc39.es/ecma262/multipage/indexed-collections.html

Fills all elements of an array from a start index to an end index with a static value. The start and end arguments are optional and can be negative, in which case they are treated as length + start or length + end.

```APIDOC
## Array.prototype.fill ( value [ , start [ , end ] ] )

### Description
Fills all elements of an array from a start index to an end index with a static value. The start and end arguments are optional and can be negative, in which case they are treated as length + start or length + end.

### Method
fill

### Parameters
- **value** (any) - Required - The value to fill the array with.
- **start** (number) - Optional - The index to start filling from. If negative, treated as length + start. Defaults to 0.
- **end** (number) - Optional - The index to stop filling (exclusive). If negative, treated as length + end. Defaults to the length of the array.

### Return Value
Returns the modified array (the this value).

### Notes
- This method is intentionally generic; it does not require that its this value be an Array. Therefore it can be transferred to other kinds of objects for use as a method.

```

--------------------------------

### Array.prototype.slice ( start, end )

Source: https://tc39.es/ecma262/multipage/indexed-collections.html

Returns a new array containing the elements from the original array from start up to, but not including, end. If end is undefined, it goes to the end of the array. Negative start and end are treated as length + start and length + end respectively.

```APIDOC
## Array.prototype.slice ( start, end )

### Description
Returns a new array containing the elements from the original array from start up to, but not including, end. If end is undefined, it goes to the end of the array. Negative start and end are treated as length + start and length + end respectively.

### Method
slice(start, end)

### Parameters
- **start** (number) - Required - The index at which to begin extraction. If negative, treated as length + start.
- **end** (number) - Optional - The index before which to end extraction. If negative, treated as length + end. If undefined, extraction goes to the end of the array.

### Return Value
- A new array containing the extracted elements.

### Behavior
- Converts `this` to an object.
- Gets the length of the array-like object.
- Clamps start and end to valid indices.
- Creates a new array using ArraySpeciesCreate.
- Copies elements from the original array to the new array.
- Sets the length of the new array and returns it.

### Note 1
The explicit setting of the "length" property is intended to ensure the length is correct even when the new array is not a built-in Array.

### Note 2
This method is intentionally generic; it does not require that its `this` value be an Array. Therefore it can be transferred to other kinds of objects for use as a method.
```

--------------------------------

### String.prototype.padStart ( maxLength [ , fillString ] )

Source: https://tc39.es/ecma262/multipage/text-processing.html

Documentation for the String.prototype.padStart method, which pads the start of a string to a specified length.

```APIDOC
## String.prototype.padStart ( maxLength [ , fillString ] )

### Description
Pads the current string with the given fill string (repeated, if needed) so that the resulting string reaches a given length. The padding is applied from the start (left side) of the string.

### Method
padStart

### Parameters
- **maxLength** (Number) - Required - The target length of the resulting string.
- **fillString** (String) - Optional - The string to pad with. Defaults to a space (U+0020) if undefined.

### Return Value
- **String** - The padded string.

### Example
```js
"abc".padStart(10);          // "       abc"
"abc".padStart(10, "foo");   // "foofoofabc"
```
```

--------------------------------

### get DataView.prototype.byteOffset

Source: https://tc39.es/ecma262/multipage/structured-data.html

Accessor property that returns the byte offset of the DataView from the start of its ArrayBuffer. Throws a TypeError if the DataView is out of bounds.

```APIDOC
## GET DataView.prototype.byteOffset

### Description
Returns the byte offset of the DataView from the start of its ArrayBuffer. Throws a TypeError if the DataView is out of bounds.

### Method
GET

### Endpoint
DataView.prototype.byteOffset

### Parameters
None.

### Response
#### Success Response (200)
- **byteOffset** (Number) - The byte offset of the DataView.

#### Response Example
```json
{
  "byteOffset": 0
}
```

#### Error Response (TypeError)
Throws a TypeError if the DataView is out of bounds.
```

--------------------------------

### Uint8Array.prototype.toBase64 ( [ options ] )

Source: https://tc39.es/ecma262/multipage/indexed-collections.html

Documentation for the Uint8Array.prototype.toBase64 method.

```APIDOC
## Uint8Array.prototype.toBase64 ( [ options ] )

### Description
Encodes the contents of the Uint8Array to a base64 or base64url string. Options allow selecting the alphabet and whether to omit padding.

### Method
N/A (JavaScript method)

### Endpoint
N/A

### Parameters
#### Options Object
- **alphabet** (String) - Optional - The alphabet to use: "base64" (default) or "base64url".
- **omitPadding** (Boolean) - Optional - If true, padding is omitted from the output.

### Request Example
```js
const uint8 = new Uint8Array([0xde, 0xad, 0xbe, 0xef]);
const base64 = uint8.toBase64();
const base64url = uint8.toBase64({ alphabet: "base64url", omitPadding: true });
```

### Response
#### Success Response
- Returns a String containing the base64 or base64url encoded representation.

#### Response Example
```js
"3q2+7w=="
```

### Errors
- Throws a TypeError if `alphabet` is not "base64" or "base64url".
```

--------------------------------

### String.prototype.substr ( start, length )

Source: https://tc39.es/ecma262/multipage/additional-ecmascript-features-for-web-browsers.html

Returns a substring of the string, starting at index start and running for length code units. If length is undefined, the substring extends to the end of the string. Negative start values are treated as sourceLength + start.

```APIDOC
## String.prototype.substr ( start, length )

### Description
Returns a substring of the string, starting at index start and running for length code units. If length is undefined, the substring extends to the end of the string. Negative start values are treated as sourceLength + start.

### Method
substr

### Parameters
- **start** (number) - Required - The starting index. If negative, treated as sourceLength + start.
- **length** (number) - Optional - The number of code units to include. If undefined, the substring extends to the end of the string.

### Returns
A String value containing the extracted substring.
```

--------------------------------

### String.prototype.substring ( start, end )

Source: https://tc39.es/ecma262/multipage/text-processing.html

Returns a substring of the string, starting from index start and running to, but not including, index end. Handles NaN, negative, and out-of-range arguments by clamping and swapping if start > end.

```APIDOC
## String.prototype.substring ( start, end )

### Description
Returns a substring of the string, starting from index start and running to, but not including, index end. If end is undefined, the substring runs to the end of the string. Handles NaN, negative, and out-of-range arguments by clamping and swapping if start > end.

### Method
substring

### Parameters
- **start** (Number) - Required - The index at which to begin extraction.
- **end** (Number) - Optional - The index before which to end extraction. If omitted, the substring runs to the end of the string.

### Returns
- **String** - The extracted substring.

### Algorithm Steps
1. Let thisValue be the this value.
2. Perform ? RequireObjectCoercible(thisValue).
3. Let string be ? ToString(thisValue).
4. Let length be the length of string.
5. Let finalStart be the result of clamping ? ToIntegerOrInfinity(start) between 0 and length.
6. Assert: If start is undefined, then finalStart is 0.
7. If end is undefined, let finalEnd be length; else let finalEnd be the result of clamping ? ToIntegerOrInfinity(end) between 0 and length.
8. Let from be min(finalStart, finalEnd).
9. Let to be max(finalStart, finalEnd).
10. Return the substring of string from from to to.

### Notes
- This method is intentionally generic; it does not require that its this value be a String object. Therefore, it can be transferred to other kinds of objects for use as a method.
```

--------------------------------

### Choice point ordering example: /(aa|aabaac|ba|b|c)*/.exec("aabaac")

Source: https://tc39.es/ecma262/multipage/text-processing.html

Demonstrates the choice point ordering described in Note 2, returning the array ["aaba", "ba"].

```javascript
/(aa|aabaac|ba|b|c)*/.exec("aabaac")
```

--------------------------------

### Greedy quantifier example: /a[a-z]{2,4}/.exec("abcdefghi")

Source: https://tc39.es/ecma262/multipage/text-processing.html

Shows the result of a greedy quantifier {2,4} matching as many characters as possible, returning "abcde".

```javascript
/a[a-z]{2,4}/.exec("abcdefghi")
```

--------------------------------

### Function constructor examples with different parameter formats

Source: https://tc39.es/ecma262/multipage/fundamental-objects.html

These three expressions are equivalent and create a function that returns the sum of its parameters. They show that the Function constructor accepts parameters either as separate arguments or as a comma-separated string.

```javascript
new Function("a", "b", "c", "return a+b+c")
```

```javascript
new Function("a, b, c", "return a+b+c")
```

```javascript
new Function("a,b", "c", "return a+b+c")
```

--------------------------------

### String.prototype.trimStart()

Source: https://tc39.es/ecma262/multipage/text-processing.html

Removes whitespace from the beginning of a string. This method is generic and can be transferred to other objects.

```APIDOC
## String.prototype.trimStart ( )

### Description
This method interprets a String value as a sequence of UTF-16 encoded code points and removes whitespace from the start of the string. It is intentionally generic and does not require its this value to be a String object.

### Method
- (none specified)

### Endpoint
- (not applicable)

### Parameters
- (none)

### Request Example
- (not applicable)

### Response
#### Success Response
- Returns a new String with leading whitespace removed.

#### Response Example
- (not provided)
```
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