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Generic JavaScript helpers that can be used with any template engine. Handlebars, Lo-Dash, Underscore, or any engine that supports helper functions.

Please consider following this project's author, Jon Schlinkert, and consider starring the project to show your ❤️ and support.

Install

Install with npm:

$ npm install --save template-helpers

Usage

To get all helpers:

const helpers = require('template-helpers')();
console.log(helpers);

Get a specific helper category

// get only the math helpers
const helpers = require('template-helpers')('math');

Get multiple helper categories

// get only the math helpers
const helpers = require('template-helpers')(['math', 'string']);

Template-engine agnostic

Lo-Dash Example

const helpers = require('template-helpers')('array');

// pass helpers on `imports`
const imports = { imports: helpers };

// compile a template
const fn = _.template('<%= first(foo) %>', imports);

// render
fn({ foo: ['a', 'b', 'c'] });
//=> 'a'

Namespacing

Handlebars and Lo-Dash both allow dot notation to be used for referencing helpers. I'd be happy to add examples for other engines if someone wants to do a PR.

Example

<%= path.dirname("a/b/c/d.js") %>

This can be used as a way of working around potential naming conflicts.

Helpers

(The following API Table of Contents is generated by verb. See the verbfile.js for more details.)

Categories

Currently 101 helpers in 10 categories:

All helpers

Visit the: code | unit tests | issues)

Visit the: code | unit tests | issues)

Visit the: code | unit tests | issues)

Visit the: code | unit tests | issues)

Visit the: code | unit tests | issues)

Visit the: code | unit tests | issues)

Visit the: code | unit tests | issues)

Visit the: code | unit tests | issues)

Visit the: code | unit tests | issues)

Visit the: code | unit tests | issues)

array

Returns true if value is an array.

Params

  • value {any}: The value to test.
  • returns {Boolean}

Example

<%= isArray('a, b, c') %>
//=> 'false'

<%= isArray(['a, b, c']) %>
//=> 'true'

Cast val to an array.

Params

  • val {any}: The value to arrayify.
  • returns {Array}: An array.
  • returns {Array}

Example

<%= arrayify('a') %>
//=> '["a"]'

<%= arrayify({a: 'b'}) %>
//=> '[{a: "b"}]'

<%= arrayify(['a']) %>
//=> '["a"]'

Returns the first item, or first n items of an array.

Params

  • array {Array}
  • n {Number}: Number of items to return, starting at 0.
  • returns {Array}

Example

<%= first(['a', 'b', 'c', 'd', 'e'], 2) %>
//=> '["a", "b"]'

Returns the last item, or last n items of an array.

Params

  • array {Array}
  • n {Number}: Number of items to return, starting with the last item.
  • returns {Array}

Example

<%= last(['a', 'b', 'c', 'd', 'e'], 2) %>
//=> '["d", "e"]'

Returns all of the items in an array up to the specified number Opposite of <%= after() %.

Params

  • array {Array}
  • n {Number}
  • returns {Array}: Array excluding items after the given number.

Example

<%= before(['a', 'b', 'c'], 2) %>
//=> '["a", "b"]'

Returns all of the items in an arry after the specified index. Opposite of <%= before() %.

Params

  • array {Array}: Collection
  • n {Number}: Starting index (number of items to exclude)
  • returns {Array}: Array exluding n items.

Example

<%= after(['a', 'b', 'c'], 1) %>
//=> '["c"]'

Calling fn on each element of the given array with the given context.

Assuming that double has been registered as a helper:

Params

  • array {Array}
  • fn {String}: The function to call on each element in the given array.
  • returns {String}

Examples

function double(str) {
  return str + str;
}
<%= each(['a', 'b', 'c'], double, ctx) %>
//=> '["aa", "bb", "cc"]'

Returns a new array, created by calling function on each element of the given array.

Assuming that double has been registered as a helper:

Params

  • array {Array}
  • fn {String}: The function to call on each element in the given array.
  • returns {String}

Examples

function double(str) {
  return str + str;
}
<%= map(['a', 'b', 'c'], double) %>
//=> '["aa", "bb", "cc"]'

Join all elements of array into a string, optionally using a given separator.

Params

  • array {Array}
  • sep {String}: The separator to use.
  • returns {String}

Example

<%= join(['a', 'b', 'c']) %>
//=> 'a, b, c'

<%= join(['a', 'b', 'c'], '-') %>
//=> 'a-b-c'

Sort the given array. If an array of objects is passed, you may optionally pass a key to sort on as the second argument. You may alternatively pass a sorting function as the second argument.

Params

  • array {Array}: the array to sort.
  • key {String|Function}: The object key to sort by, or sorting function.

Example

<%= sort(["b", "a", "c"]) %>
//=> 'a,b,c'

<%= sort([{a: "zzz"}, {a: "aaa"}], "a") %>
//=> '[{"a":"aaa"},{"a":"zzz"}]'

Returns the length of the given array.

Params

  • array {Array}
  • returns {Number}: The length of the array.

Example

<%= length(['a', 'b', 'c']) %>
//=> 3

Returns an array with all falsey values removed.

Params

  • arr {Array}
  • returns {Array}

Example

<%= compact([null, a, undefined, 0, false, b, c, '']) %>
//=> '["a", "b", "c"]'

Return the difference between the first array and additional arrays.

Params

  • array {Array}: The array to compare againts.
  • arrays {Array}: One or more additional arrays.
  • returns {Array}

Example

<%= difference(["a", "c"], ["a", "b"]) %>
//=> '["c"]'

Return an array, free of duplicate values.

Params

  • array {Array}: The array to uniquify
  • returns {Array}: Duplicate-free array

Example

<%= unique(['a', 'b', 'c', 'c']) %
=> '["a", "b", "c"]'

Returns an array of unique values using strict equality for comparisons.

Params

  • arr {Array}
  • returns {Array}

Example

<%= union(["a"], ["b"], ["c"]) %>
//=> '["a", "b", "c"]'

Shuffle the items in an array.

Params

  • arr {Array}
  • returns {Array}

Example

<%= shuffle(["a", "b", "c"]) %>
//=> ["c", "a", "b"]

code

Embed code from an external file as preformatted text.

Params

  • fp {String}: filepath to the file to embed.
  • language {String}: Optionally specify the language to use for syntax highlighting.
  • returns {String}

Example

<%= embed('path/to/file.js') %>

// specify the language to use
<%= embed('path/to/file.hbs', 'html') %>

Generate the HTML for a jsFiddle link with the given params

Params

  • params {Object}
  • returns {String}

Example

<%= jsfiddle({id: '0dfk10ks', {tabs: true}}) %>

collection

Returns true if value exists in the given string, array or object. See any for documentation.

Params

  • value {any}
  • target {any}
  • options {Object}

Filter the given array or object to contain only the matching values.

Params

  • arr {Array}
  • returns {Array}

Example

<%= filter(['foo', 'bar', 'baz']) %>
//=> '["a", "b", "c"]'

conditional

Returns true when both valueA and valueB are truthy.

Params

  • valueA {any}
  • valueB {any}
  • returns {Boolean}

Render a block when a comparison of the first and third arguments returns true.

Params

  • valueA {String}
  • operator {String}: The operator to use for the comparison (must be a quoted string).
  • valueB {String}
  • returns {Boolean}

Example

<%= compare("foo", "!==", "bar") %>

Returns the first truthy value.

Params

  • ...values {...args}
  • returns {any}

Returns true when all provided values are truthy.

Params

  • ...values {...any}
  • returns {Boolean}

Returns true when valueA is greater than valueB.

Params

  • valueA {String}
  • valueB {String}
  • returns {Boolean}

Returns true when valueA is greater than or equal to valueB.

Params

  • valueA {String}
  • valueB {String}
  • returns {Boolean}

Return true if key is an own, enumerable property of the given obj.

Params

  • object {Object}
  • key {String}
  • returns {Boolean}

Returns true when valueA equals valueB.

Params

  • valueA {String}
  • valueB {String}
  • strict {String}
  • returns {Boolean}

Alias for is.

Params

  • valueA {String}
  • valueB {String}
  • strict {String}
  • returns {Boolean}

Returns true when valueA does not equal valueB.

Params

  • valueA {String}
  • valueB {String}
  • returns {Boolean}

Alias for isnt.

Params

  • valueA {String}
  • valueB {String}
  • returns {Boolean}

Returns true when valueA is less than valueB.

Params

  • valueA {String}
  • valueB {String}
  • returns {Boolean}

Returns true when valueA is less than or equal to valueB.

Params

  • valueA {String}
  • valueB {String}
  • returns {Boolean}

Returns valueA if thruthy, otherwise valueB.

Params

  • valueA {any}
  • valueB {any}
  • returns {any}

Returns true when at least one value is truthy.

Params

  • ...values {...any}
  • returns {Boolean}

fs

Return true if a file exists

Params

  • filepath {String}: Path of the file to check.
  • returns {Boolean}: True if the file exists

Example

<%= exists("foo.js") %>

Read a file from the file system and inject its content

Params

  • filepath {String}: Path of the file to read.
  • returns {String}: Contents of the given file.

Example

<%= read("foo.js") %>

html

Escape HTML characters in a string.

Params

  • str {String}: String of HTML with characters to escape.
  • returns {String}

Example

<%= escapeHtml("<span>foo</span>") %>
//=> &lt;span&gt;foo&lt;&#x2F;span&gt;

Strip HTML tags from a string, so that only the text nodes are preserved.

Params

  • str {String}: The string of HTML to sanitize.
  • returns {String}

Example

<%= sanitize("<span>foo</span>") %>
//=> 'foo'

math

Return the product of a plus b.

Params

  • a {Number}
  • b {Number}

Example

<%= add(1, 2) %>
//=> '3'

Subtract b from a.

Params

  • a {Number}
  • b {Number}

Example

<%= subtract(5, 2) %>
//=> '3'

Divide a (the numerator) by b (the divisor).

Params

  • a {Number}: the numerator.
  • b {Number}: the divisor.
  • returns {Number}: The quotient of a divided by b.

Example

<%= divide(10, 2) %>
//=> '5'

Multiply a by b.

Params

  • a {Number}
  • b {Number}
  • returns {Number}: The product of a times b.

Example

<%= divide(10, 2) %>
//=> '5'

Returns the largest integer less than or equal to the given number.

Params

  • number {Number}
  • returns {Number}

Example

<%= floor(10.6) %>
//=> '10'

Returns the smallest integer greater than or equal to the given number.

Params

  • number {Number}
  • returns {Number}

Example

<%= ceil(10.1) %>
//=> '11'

Returns the value of the given number rounded to the nearest integer.

Params

  • number {Number}
  • returns {Number}

Example

<%= round(10.1) %>
//=> '10'

<%= round(10.5) %>
//=> '11'

Returns the sum of all numbers in the given array.

Params

  • number {Number}
  • returns {Number}

Example

<%= sum([1, 2, 3, 4, 5]) %>
//=> '15'

object

Specify a fallback value to use when the desired value is undefined. Note that undefined variables that are not object properties with throw an error.

Params

  • a {any}: The desired value.
  • b {any}: The fallback ("default") value
  • returns {any}: Either a or b

Example

// when `title` is undefined, use the generic `site.title`
<%= fallback(page.title, site.title) %>

Stringify an object using JSON.stringify().

Params

  • object {Object}
  • returns {String}

Example

<%= stringify({a: "a"}) %>
//=> '{"a":"a"}'

Parse a string into an object using JSON.parse().

Params

  • str {String}: The string to parse.
  • returns {Object}: The parsed object.

Example

<%= parse('{"foo":"bar"}')["foo"] %>
//=> 'bar'

Use property paths (a.b.c) get a nested value from an object.

Params

  • object {Object}
  • path {String}: Dot notation for the property to get.
  • returns {String}

Example

<%= get({a: {b: 'c'}}, 'a.b') %>
//=> 'c'

Returns an array of keys from the given object.

Params

  • object {Object}
  • returns {Array}: Keys from object

Example

<%= keys({a: 'b', c: 'd'}) %>
//=> '["a", "c"]'

Return true if the given value is an object, and not null or an array.

Params

  • value {Object}: The value to check.
  • returns {Boolean}

Example

<%= isObject(['a', 'b', 'c']) %>
//=> 'false'

<%= isObject({a: 'b'}) %>
//=> 'true'

Return true if the given value is a plain object.

Params

  • value {Object}: The value to check.
  • returns {Boolean}

Example

<%= isPlainObject(['a', 'b', 'c']) %>
//=> 'false'

<%= isPlainObject({a: 'b'}) %>
//=> 'true'

<%= isPlainObject(/foo/g) %>
//=> 'false'

Return true if key is an own, enumerable property of the given obj.

Params

  • object {Object}
  • key {String}
  • returns {Boolean}

Return a copy of object exclusing the given keys.

Params

  • object {Object}: Object with keys to omit.
  • keys {String}: Keys to omit.
  • returns {Boolean}

Example

<%= omit({a: 'a', b: 'b', c: 'c'}, ['a', 'c']) %>
//=> '{b: "b"}'

Iterate over the own and inherited enumerable properties of an object, and return an object with properties that evaluate to true from the callback. Exit early by returning false.

Params

  • object {Object}: Object with keys to omit.
  • keys {String}: Keys to omit.
  • returns {Boolean}

Example

const context = { values: { a: 'b', c: 'd' } };
const str = '<% forIn(values, function(val, key) { %><%= val %><% }) %>';
const fn = _.template(str, { imports: helpers });
assert.equal(fn(context), 'bd');

Iterate over the own enumerable properties of an object, and return an object with properties that evaluate to true from the callback. Exit early by returning false

Params

  • object {Object}: Object with keys to omit.
  • keys {String}: Keys to omit.
  • returns {Boolean}

Example

const context = { values: { a: 'b', c: 'd' } };
const str = '<% forOwn(values, function(val, key) { %><%= key %><% }) %>';
const fn = _.template(str, { imports: helpers });
console.log(fn(context)) //=> 'ac'

Extend o with properties of other objects.

Params

  • o {Object}: The target object. Pass an empty object to shallow clone.
  • objects {Object}
  • returns {Object}

Recursively combine the properties of o with the properties of other objects.

Params

  • o {Object}: The target object. Pass an empty object to shallow clone.
  • objects {Object}
  • returns {Object}

path

Return the dirname for the given filepath. Uses the node.js path module.

Params

  • filepath {String}
  • returns {String}: Returns the directory part of the file path.

Example

<%= dirname("a/b/c/d") %>
//=> 'a/b/c'

Return the basename for the given filepath. Uses the node.js path module.

Params

  • filepath {String}
  • returns {String}: Returns the basename part of the file path.

Example

<%= basename("a/b/c/d.js") %>
//=> 'd.js'

Returns the filename for the given filepath, excluding extension. Aliased as stem.

Params

  • filepath {String}
  • returns {String}: Returns the file name part of the file path.

Example

<%= filename("a/b/c/d.js") %>
//=> 'd'

Alias for filename.

Params

  • filepath {String}
  • returns {String}: Returns the file name part of the file path.

Example

<%= stem("a/b/c/d.js") %>
//=> 'd'

Return the file extension for the given filepath. Uses the node.js path module.

Params

  • filepath {String}
  • returns {String}: Returns a file extension

Example

<%= extname("foo.js") %>
//=> '.js'

Return the file extension for the given filepath, excluding the ..

Params

  • filepath {String}
  • returns {String}: Returns a file extension without dot.

Example

<%= ext("foo.js") %>
//=> 'js'

Resolves the given paths to an absolute path. Uses the node.js path module.

Params

  • filepath {String}
  • returns {String}: Returns a resolve

Example

<%= resolve('/foo/bar', './baz') %>
//=> '/foo/bar/baz'

Get the relative path from file a to file b. Typically a and b would be variables passed on the context. Uses the node.js path module.

Params

  • a {String}: The "from" file path.
  • b {String}: The "to" file path.
  • returns {String}: Returns a relative path.

Example

<%= relative(a, b) %>

Get specific (joined) segments of a file path by passing a range of array indices.

Params

  • filepath {String}: The file path to split into segments.
  • returns {String}: Returns a single, joined file path.

Example

<%= segments("a/b/c/d", "2", "3") %>
//=> 'c/d'

<%= segments("a/b/c/d", "1", "3") %>
//=> 'b/c/d'

<%= segments("a/b/c/d", "1", "2") %>
//=> 'b/c'

Join all arguments together and normalize the resulting filepath. Uses the node.js path module.

Note: there is also a join() array helper, dot notation can be used with helpers to differentiate. Example: <%= path.join() %>.

Params

  • filepaths {String}: List of file paths.
  • returns {String}: Returns a single, joined file path.

Example

<%= join("a", "b") %>
//=> 'a/b'

Returns true if a file path is an absolute path. An absolute path will always resolve to the same location, regardless of the working directory. Uses the node.js path module.

Params

  • filepath {String}
  • returns {String}: Returns a resolve

Example

// posix
<%= isAbsolute('/foo/bar') %>
//=> 'true'
<%= isAbsolute('qux/') %>
//=> 'false'
<%= isAbsolute('.') %>
//=> 'false'

// Windows
<%= isAbsolute('//server') %>
//=> 'true'
<%= isAbsolute('C:/foo/..') %>
//=> 'true'
<%= isAbsolute('bar\\baz') %>
//=> 'false'
<%= isAbsolute('.') %>
//=> 'false'

Returns true if a file path is an absolute path. An absolute path will always resolve to the same location, regardless of the working directory. Uses the node.js path module.

Params

  • filepath {String}
  • returns {String}: Returns a resolve

Example

// posix
<%= isRelative('/foo/bar') %>
//=> 'false'
<%= isRelative('qux/') %>
//=> 'true'
<%= isRelative('.') %>
//=> 'true'

// Windows
<%= isRelative('//server') %>
//=> 'false'
<%= isRelative('C:/foo/..') %>
//=> 'false'
<%= isRelative('bar\\baz') %>
//=> 'true'
<%= isRelative('.') %>
//=> 'true'

string

camelCase the characters in string.

Params

  • string {String}: The string to camelcase.
  • returns {String}

Example

<%= camelcase("foo bar baz") %>
//=> 'fooBarBaz'

Center align the characters in a string using non-breaking spaces.

Params

  • str {String}: The string to reverse.
  • returns {String}: Centered string.

Example

<%= centerAlign("abc") %>

Like trim, but removes both extraneous whitespace and non-word characters from the beginning and end of a string.

Params

  • string {String}: The string to chop.
  • returns {String}

Example

<%= chop("_ABC_") %>
//=> 'ABC'

<%= chop("-ABC-") %>
//=> 'ABC'

<%= chop(" ABC ") %>
//=> 'ABC'

Count the number of occurrances of a substring within a string.

Params

  • string {String}
  • substring {String}
  • returns {Number}: The occurances of substring in string

Example

<%= count("abcabcabc", "a") %>
//=> '3'

dot.case the characters in string.

Params

  • string {String}
  • returns {String}

Example

<%= dotcase("a-b-c d_e") %>
//=> 'a.b.c.d.e'

Truncate a string to the specified length, and append it with an elipsis, .

Params

  • str {String}
  • length {Number}: The desired length of the returned string.
  • ch {String}: Optionally pass custom characters to append. Default is .
  • returns {String}: The truncated string.

Example

<%= ellipsis("<span>foo bar baz</span>", 7) %>
//=> 'foo bar…'

Returns true if the value is a string.

Params

  • val {String}
  • returns {Boolean}: True if the value is a string.

Example

<%= isString('abc') %>
//=> 'true'

<%= isString(null) %>
//=> 'false'

Lowercase the characters in the given string.

Params

  • string {String}: The string to lowercase.
  • returns {String}

Example

<%= lowercase("ABC") %>
//=> 'abc'

PascalCase the characters in string.

Params

  • string {String}
  • returns {String}

Example

<%= pascalcase("foo bar baz") %>
//=> 'FooBarBaz'

snake_case the characters in string.

Params

  • string {String}
  • returns {String}

Example

<%= snakecase("a-b-c d_e") %>
//=> 'a_b_c_d_e'

Split string by the given character.

Params

  • string {String}: The string to split.
  • returns {String} character: Default is ,

Example

<%= split("a,b,c", ",") %>
//=> ['a', 'b', 'c']

Strip substring from the given string.

Params

  • substring {String|RegExp}: The string or regex pattern of the substring to remove.
  • string {String}: The target string.

Example

<%= strip("foo-bar", "foo-") %>
//=> 'bar'

Strip the indentation from a string.

Params

  • string {String}: The string to strip indentation from.
  • returns {String}

Example

<%= stripIndent("  _ABC_") %>
//=> 'ABC'

Trim extraneous whitespace from the beginning and end of a string.

Params

  • string {String}: The string to trim.
  • returns {String}

Example

<%= trim("  ABC   ") %>
//=> 'ABC'

dash-case the characters in string. This is similar to slugify, but slugify makes the string compatible to be used as a URL slug.

Params

  • string {String}
  • returns {String}

Example

<%= dashcase("a b.c d_e") %>
//=> 'a-b-c-d-e'

path/case the characters in string.

Params

  • string {String}
  • returns {String}

Example

<%= pathcase("a-b-c d_e") %>
//=> 'a/b/c/d/e'

Sentence-case the characters in string.

Params

  • string {String}
  • returns {String}

Example

<%= sentencecase("foo bar baz.") %>
//=> 'Foo bar baz.'

Replace spaces in a string with hyphens. This

Params

  • string {String}
  • returns {String}

Example

<%= hyphenate("a b c") %>
//=> 'a-b-c'

Reverse the characters in a string.

Params

  • str {String}: The string to reverse.
  • returns {String}

Example

<%= reverse("abc") %>
//=> 'cba'

Right align the characters in a string using non-breaking spaces.

Params

  • str {String}: The string to reverse.
  • returns {String}: Right-aligned string.

Example

<%= rightAlign(str) %>

Replace occurrences of a with b.

Params

  • str {String}
  • a {String|RegExp}: Can be a string or regexp.
  • b {String}
  • returns {String}

Example

<%= replace("abcabc", /a/, "z") %>
//=> 'zbczbc'

Truncate a string by removing all HTML tags and limiting the result to the specified length.

Params

  • str {String}
  • length {Number}: The desired length of the returned string.
  • returns {String}: The truncated string.

Example

<%= titlecase("big deal") %>
//=> 'foo bar'

Truncate a string by removing all HTML tags and limiting the result to the specified length.

Params

  • str {String}
  • length {Number}: The desired length of the returned string.
  • returns {String}: The truncated string.

Example

<%= truncate("<span>foo bar baz</span>", 7) %>
//=> 'foo bar'

Uppercase the characters in a string.

Params

  • string {String}: The string to uppercase.
  • returns {String}

Example

<%= uppercase("abc") %>
//=> 'ABC'

Wrap words to a specified width using word-wrap.

Params

  • string {String}: The string with words to wrap.
  • object {Options}: Options to pass to word-wrap
  • returns {String}: Formatted string.

Example

<%= wordwrap("a b c d e f", {width: 5, newline: '<br>  '}) %>
//=> '  a b c <br>  d e f'

Coverage

Statements   : 94.61% ( 439/464 )
Branches     : 88.37% ( 190/215 )
Functions    : 96.94% ( 95/98 )
Lines        : 94.42% ( 389/412 )

About

Contributing

Pull requests and stars are always welcome. For bugs and feature requests, please create an issue.

Running Tests

Running and reviewing unit tests is a great way to get familiarized with a library and its API. You can install dependencies and run tests with the following command:

$ npm install && npm test
Building docs

(This project's readme.md is generated by verb, please don't edit the readme directly. Any changes to the readme must be made in the .verb.md readme template.)

To generate the readme, run the following command:

$ npm install -g verbose/verb#dev verb-generate-readme && verb

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You might also be interested in the following projects (also visit the github.com/helpers, where you can find 60+ additional standalone helpers!):

  • assemble: Get the rocks out of your socks! Assemble makes you fast at creating web projects… more | homepage
  • handlebars-helpers: More than 130 Handlebars helpers in ~20 categories. Helpers can be used with Assemble, Generate… more | homepage
  • templates: System for creating and managing template collections, and rendering templates with any node.js template engine… more | homepage

Contributors

Author

Jon Schlinkert

License

Copyright © 2018, Jon Schlinkert. Released under the MIT License.


This file was generated by verb-generate-readme, v0.8.0, on November 24, 2018.

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Generic JavaScript helpers that can be used with any template engine. Handlebars, Lo-Dash, Underscore, or any engine that supports helper functions.

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