heredocument
v2.0.2
Published
Here document built on ES2015 template string literals like Ruby's <<~
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Here Document Using ES2015 Template String
This package provides heredoc as tag of ES2015 Template String.
It trims white spaces in the template string and strips common indentation like <<~
in Ruby.
This package has no dependency.
const heredoc = require('heredocument');
function showError(err) {
const msg = heredoc`
Error: ${err.message}
Expected: ${err.expected}
Actual : ${err.actual}
`;
assert.equal(msg, 'Error: blah blah\n\n Expected: foo\n Actual : bar\n');
console.log(msg);
}
Without this package, we need to care about indentation of the string.
const msg = `Error: ${err.message}
Expected: ${err.expected}
Actual : ${err.actual}
`;
Installation
Available via npm.
$ npm install heredocument
- commonjs
const heredoc = require('heredocument');
- ES6 Modules
import heredoc from 'heredocument';
- Browser
<script src="/path/to/heredocument/index.js"></script>
<script>
const heredoc = window.Heredoc;
</script>
Usage
By default, a heredoc tag for template strings is exported. Almost all cases, you can use it out of box.
const heredoc = require('heredocument');
console.log(`
foo
bar
piyo
`);
This package cares about tab (\t
) character. By default, tab character is handled as 8 whitespaces.
If the indentation is split at the middle of tab character, it will be split into white spaces.
const heredoc = require('heredocument');
assert.equal(heredoc`\tfoo\t bar\t\tpiyo`, 'foo\n bar \npiyo');
And default newline is NL (\n
).
These behaviors can be customized. There are two options; tabSize
, inputNewline
and outputNewline
.
const heredoc = require('heredocument')({
tabSize: 4,
inputNewline: '\n\r',
outputNewline: '\n\r',
});
assert.equal(
heredoc`
FOO
BAR
BAZ
`,
'FOO\n BAR\n\tBAZ\n'
);
// => OK
- tabSize : The number of whitespaces for 1 tab character (
\t
). Default is8
. - inputNewline : The newline character to split the string into lines. Default value is
\n
. - outputNewline : The newline character used in output string. If not specified, value of
inputNewline
is used. Default value is\n
. - newlineAtEnd : EOL should be added at the end of string or not. If
true
, newline will be added at the end. Default value istrue
.
For example, below oneline
tag replaces all newlines in input hence it can create single line string from multiline template string.
const heredoc = require('heredocument');
const oneline = heredoc({
inputNewline: '\n',
outputNewline: ' ',
newlineAtEnd: false
});
const msg = oneline`
This message is too long. So we need to split the string literal such as
"blah blah" + "blah blah". But with this 'oneline' tag, all newlines
(including intepolated string) are removed and you can get oneline
string.
`;
assert.equal(msg, `This message is too long. So we need to split the string literal such as "blah blah" + "blah blah". But with this 'oneline' tag, all newlines (including intepolated string) are removed and you can get oneline string.`);
// => OK
Development
$ git clone https://github.com/rhysd/heredocument.git && cd ./heredocument
$ npm install # Install all dependencies
$ npm run lint # Run linter
$ npm test # Run tests with mocha
$ npm bench # Run benchmark
$ npm profile # Run profiling
License
Distributed under the MIT license.