esutils

esutils (esutils) is utility box for ECMAScript language tools.

## API

## ast

### ast.isExpression(node)

Returns true if `node` is an Expression as defined in ECMA262 edition 5.1 section 11.

### ast.isStatement(node)

Returns true if `node` is a Statement as defined in ECMA262 edition 5.1 section 12.

### ast.isIterationStatement(node)

Returns true if `node` is an IterationStatement as defined in ECMA262 edition 5.1 section 12.6.

### ast.isSourceElement(node)

Returns true if `node` is a SourceElement as defined in ECMA262 edition 5.1 section 14.

### ast.trailingStatement(node)

Returns `Statement?` if `node` has trailing `Statement`.

if (cond)
consequent;

When taking this `IfStatement`, returns `consequent;` statement.

### ast.isProblematicIfStatement(node)

Returns true if `node` is a problematic IfStatement. If `node` is a problematic `IfStatement`, `node` cannot be represented as an one on one JavaScript code.

{
type: 'IfStatement',
consequent: {
type: 'WithStatement',
body: {
type: 'IfStatement',
consequent: {type: 'EmptyStatement'}
}
},
alternate: {type: 'EmptyStatement'}
}

The above node cannot be represented as a JavaScript code, since the top level `else` alternate belongs to an inner `IfStatement`.

## code

### code.isDecimalDigit(code)

Return true if provided code is decimal digit.

### code.isHexDigit(code)

Return true if provided code is hexadecimal digit.

### code.isOctalDigit(code)

Return true if provided code is octal digit.

### code.isWhiteSpace(code)

Return true if provided code is white space. White space characters are formally defined in ECMA262.

### code.isLineTerminator(code)

Return true if provided code is line terminator. Line terminator characters are formally defined in ECMA262.

### code.isIdentifierStart(code)

Return true if provided code can be the first character of ECMA262 Identifier. They are formally defined in ECMA262.

### code.isIdentifierPart(code)

Return true if provided code can be the trailing character of ECMA262 Identifier. They are formally defined in ECMA262.

## keyword

### keyword.isKeywordES5(id, strict)

Returns `true` if provided identifier string is a Keyword or Future Reserved Word in ECMA262 edition 5.1. They are formally defined in ECMA262 sections 7.6.1.1 and 7.6.1.2, respectively. If the `strict` flag is truthy, this function additionally checks whether `id` is a Keyword or Future Reserved Word under strict mode.

### keyword.isKeywordES6(id, strict)

Returns `true` if provided identifier string is a Keyword or Future Reserved Word in ECMA262 edition 6. They are formally defined in ECMA262 sections 11.6.2.1 and 11.6.2.2, respectively. If the `strict` flag is truthy, this function additionally checks whether `id` is a Keyword or Future Reserved Word under strict mode.

### keyword.isReservedWordES5(id, strict)

Returns `true` if provided identifier string is a Reserved Word in ECMA262 edition 5.1. They are formally defined in ECMA262 section 7.6.1. If the `strict` flag is truthy, this function additionally checks whether `id` is a Reserved Word under strict mode.

### keyword.isReservedWordES6(id, strict)

Returns `true` if provided identifier string is a Reserved Word in ECMA262 edition 6. They are formally defined in ECMA262 section 11.6.2. If the `strict` flag is truthy, this function additionally checks whether `id` is a Reserved Word under strict mode.

### keyword.isRestrictedWord(id)

Returns `true` if provided identifier string is one of `eval` or `arguments`. They are restricted in strict mode code throughout ECMA262 edition 5.1 and in ECMA262 edition 6 section 12.1.1.

### keyword.isIdentifierNameES5(id)

Return true if provided identifier string is an IdentifierName as specified in ECMA262 edition 5.1 section 7.6.

### keyword.isIdentifierNameES6(id)

Return true if provided identifier string is an IdentifierName as specified in ECMA262 edition 6 section 11.6.

### keyword.isIdentifierES5(id, strict)

Return true if provided identifier string is an Identifier as specified in ECMA262 edition 5.1 section 7.6. If the `strict` flag is truthy, this function additionally checks whether `id` is an Identifier under strict mode.

### keyword.isIdentifierES6(id, strict)

Return true if provided identifier string is an Identifier as specified in ECMA262 edition 6 section 12.1. If the `strict` flag is truthy, this function additionally checks whether `id` is an Identifier under strict mode.

## License

Copyright (C) 2013 Yusuke Suzuki (twitter: @Constellation) and other contributors.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

- Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
- Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.