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Grapheme JS

Grapheme clustering for JavaScript with Unicode Standard Annex #29 compliance and some custom emoji enhancements.

Usage Example

var graphemejs = require('graphemejs').useCustomClustering();
 
// Ensures that the given string does not contain more than the given max number of visible
// characters.
function assertMaxCharLength(str, maxLength) {
  var graphemeClusters = graphemejs.extract(str);
  
  if (graphemeClusters.length > maxLength) {
    throw new Error('String contains too many characters.');
  }
}

---

graphemejs

var graphemejs = require('graphemejs');

The main library. Provides access to the utils and some convenience functions.

extract

graphemejs.extract(str, [useLegacyClustering, [useCustomClustering]])

Alias of stringUtil.extractGraphemeClusters.

useLegacyClustering

graphemejs.useLegacyClustering()

Sets defaults.useLegacyClustering to true (see Defaults).

Returns graphemejs so it can be chained and used on the require line like so:

var graphemejs = require('graphemejs').useLegacyClustering();

useCustomClustering

graphemejs.useCustomClustering()

Sets defaults.useCustomClustering to true (see Defaults).

Returns graphemejs so it can be chained and used on the require line like so:

var graphemejs = require('graphemejs').useCustomClustering();

Properties

Name	Description
graphemejs.stringUtil	The String Util.
graphemejs.debugUtil	The Debug Util.
graphemejs.codePointUtil	The Code Point Util.
graphemejs.graphemeClusterUtil	The Grapheme Cluster Util.
graphemejs.surrogatePairUtil	The Surrogate Pair Util.
graphemejs.defaults	The Defaults.

---

String Util

var stringUtil = graphemejs.stringUtil;

Provides functions for interfacing with strings. These functions can be used to interface with strings on the grapheme cluster level rather than on the code unit (character) level.

extractGraphemeClusters

stringUtil.extractGraphemeClusters(str, [useLegacyClustering, [useCustomClustering]])

Parameter	Type	Description
str	string	The string to extract grapheme clusters from.
useLegacyClustering	boolean	Optional - If legacy (true) or extended (false) grapheme clusters should be used (see Clustering Variants). Defaults to defaults.useLegacyClustering (see Defaults).
useCustomClustering	boolean	Optional - If custom clustering should be applied to the grapheme clusters (true) or not (false) (see Clustering Variants). Defaults to defaults.useCustomClustering (see Defaults).

Decodes the given string into code points and groups them into grapheme clusters.

Returns int[][] an array of grapheme clusters extracted from the given string.

buildStringFromGraphemeClusters

stringUtil.buildStringFromGraphemeClusters(graphemeClusters)

Parameter	Type	Description
graphemeClusters	int[][]	Grapheme clusters to create a string from.

Encodes all the code points from the given grapheme clusters into a string.

Returns string a string built from the given grapheme clusters.

sliceGraphemeClusters

stringUtil.sliceGraphemeClusters(str, [start, [end, [useLegacyClustering, [useCustomClustering]]]])

Parameter	Type	Description
str	string	String to slice.
start	int	Optional - Where to start slicing from. This is passed as the first paramter to the Array.slice function called on the extracted grapheme clusters.
end	int	Optional - Where to stop slicing at. This is passed as the second paramter to the Array.slice function called on the extracted grapheme clusters.
useLegacyClustering	boolean	Optional - If legacy (true) or extended (false) grapheme clusters should be used (see Clustering Variants). Defaults to defaults.useLegacyClustering (see Defaults).
useCustomClustering	boolean	Optional - If custom clustering should be applied to the grapheme clusters (true) or not (false) (see Clustering Variants). Defaults to defaults.useCustomClustering (see Defaults).

Slices the given string by grapheme clusters instead of by characters. It does this by extracting grapheme clusters from the given string, slicing them via the Array.slice function, and then building them back into a string.

NOTE: This function uses the Array.slice function internally, and not the String.slice function. Therefore, this function should not be expected to behave exactly the same as the String.slice, String.substr, nor String.substring functions. Refer to your documentation for the Array.slice function for expected behavior.

Returns string a string sliced based on its grapheme clusters.

var graphemejs = require('graphemejs').useCustomClustering();
var stringUtil = graphemejs.stringUtil;
 
// Truncates the given string if it has more than the given max number of grapheme clusters
function trancateStr(str, maxLength) {
  return stringUtil.sliceGraphemeClusters(str, 0, maxLength);
}

---

Debug Util

var debugUtil = graphemejs.debugUtil;

Provides functions for debugging strings and grapheme clusters. These functions can be used to get detailed, readable information about the content of strings and grapheme clusters.

getStringInfo

debugUtil.getStringInfo(str, [useLegacyClustering, [useCustomClustering]])

Parameter	Type	Description
str	string	String to get debug information about.
useLegacyClustering	boolean	Optional - If legacy (true) or extended (false) grapheme clusters should be used (see Clustering Variants). Defaults to defaults.useLegacyClustering (see Defaults).
useCustomClustering	boolean	Optional - If custom clustering should be applied to the grapheme clusters (true) or not (false) (see Clustering Variants). Defaults to defaults.useCustomClustering (see Defaults).

Extracts grapheme clusters from the given string and returns a string containing readable debug information about them.

Returns string a string containing debug information about the grapheme clusters in the given string.

var graphemejs = require('graphemejs').useCustomClustering();
var debugUtil = graphemejs.debugUtil;
 
var str = 'hey \uD83D\uDC71\uD83C\uDFFF you';
console.log(debugUtil.getStringInfo(str));

Console Output:

String:
Length: 12

hey  you

--------------
Code Points:
Num: 10

U+68
U+65
U+79
U+20
U+1F471 (0xD83D, 0xDC71)
U+1F3FF (0xD83C, 0xDFFF)
U+20
U+79
U+6F
U+75

--------------
Grapheme Clusters
Num: 9

0:    h     U+68
1:    e     U+65
2:    y     U+79
3:          U+20
4:         U+1F471 U+1F3FF
5:          U+20
6:    y     U+79
7:    o     U+6F
8:    u     U+75

getGraphemeClustersInfo

debugUtil.getGraphemeClustersInfo(graphemeClusters)

Parameter	Type	Description
graphemeClusters	int[][]	Grapheme clusters to get debug information about.

Buidls a string containing readable debug information about the given grapheme clusters.

Returns string a string containing debug information about the given grapheme clusters.

var graphemejs = require('graphemejs').useCustomClustering();
var debugUtil = graphemejs.debugUtil;
 
var str = 'hey \uD83D\uDC71\uD83C\uDFFF you';
var graphemeClusters = g.extract(str);
 
console.log('str: ', str);
console.log(debugUtil.getGraphemeClustersInfo(str));

Console Output:

str: hey  you
Num: 9

0:    h     U+68
1:    e     U+65
2:    y     U+79
3:          U+20
4:         U+1F471 U+1F3FF
5:          U+20
6:    y     U+79
7:    o     U+6F
8:    u     U+75

---

Defaults

var defaults = graphemejs.defaults;

Stores the default values for parameters. These default values are used globally across several functions. Each one can be set to change the default value.

This is a convience so you do not have to specify if you want to use legacy and/or custom clustering every time you call a function that needs that information. Instead, you can set the global defaults once and the functions will use those. However, you can still override the defaults by passing in a value for the associated parameters.

For example, to always use custom clustering by default you can:

var graphemejs = require('graphemejs');
 
graphemejs.extract('hello world'); // will NOT use custom clustering
 
graphemejs.defaults.useCustomClustering = true;
 
graphemejs.extract('hello world'); // WILL use custom clustering

You can also use the convenience function graphemejs.useCustomClustering when requiring graphemejs (or at any time) like so:

var graphemejs = require('graphemejs').useCustomClustering();
 
graphemejs.extract('hello world'); // WILL use custom clustering

At any time you can override the defaults like so:

var graphemejs = require('graphemejs');
 
graphemejs.extract('hello world'); // will NOT use custom clustering
graphemejs.extract('hello world', ..., true); // WILL use custom clustering
 
graphemejs.defaults.useCustomClustering = true;
 
graphemejs.extract('hello world'); // WILL use custom clustering
graphemejs.extract('hello world', ..., false); // will NOT use custom clustering
 

Properties

Name	Value	Description
defaults.useLegacyClustering	false	The default value for the useLegacyClustering parameter. Controls if legacy clustering should be used by default.
defaults.useCustomClustering	false	The default value for the useCustomClustering parameter. Controls if custom clustering should be used by default.