@xassist/xassist-array

This module provides some helperfunctions for javascript Arrays. It does not extend the native Array-object, but the extra methods are available via the array()-function.

Installation

If you use NPM, you can install the module via npm install xassist-array. Otherwise, you can download the latest minified file. Be aware any dependencies are not installed by default; you should consider downloading them yourself. If you want, you can install the complete library from github xassist, this includes all dependencies you may need.

The module uses UMD and supports AMD, CommonJS and vanilla environments. Using vanilla: the xaglobal is exported:

<script>
xa.array()
</script>

API

array()

The base function array(), gives access to the underlying methods

array(/*array:Array*/)

Parameters for array()

array() takes 1 parameters:

• baseArray [Array]:an Array on which we will execute the underlying methods.

Result for array()

array() returns 3 methods:

• pushUnique [function]: Pushes elements on the array, only if the element is unique
• groupSequence [function]: this function groups elements based on previouselement (so it is best to have an ordered array as input)
• replaceNull [function]: this function replaces all null or undefined values

Example for array()

array([1,2,3])
array(["hello","world", "!"])

array().pushUnique()

The first method array().pushUnique() will push elements onto the array, but only if their unique

array(arr).pushUnique(value [,unique::Boolean; default:true])

Parameters for array().pushUnique()

array().pushUnique() takes 2 parameters:

• value [any datatype]:is an element that you want to push on the array
• unique [Boolean,defaults to: true]:a boolean indicating if the function must check if the value allready exists

Result for array().pushUnique()

array().pushUnique() returns the length of the original array.

Example for array().pushUnique()

Suppose following initialization:

var b={yes:true};
var a=[1,2,b,{a:1},"test"]
var a2=array(a)

a2.pushUnique(1)           //a.length===5 (the element 1 exists, nothing added)
a2.pushUnique(1,false)     //a.lenght===6 (override of the unique check, so 1 is added)
a2.pushUnique({a:1})       //a.length===7 (objects should be passed by reference)
a2.pushUnique(b)           //a.length===8 (object is passed by reference, so it get's added)

This will result in:

a===[1,2,b,{a:1},"test",1,{a:1},b]

array().groupSequence()

array().groupSequence() will group the array based on a groupingfunction, which compares each value with it's predecessor.

array(arr).groupSequence(checkFn::function)

array().groupSequence() works best on a sorted array.

Parameters for array().groupSequence()

array().groupSequence() takes 1 parameters:

• checkFn [Function]:a function which compares each value of the array with it's predecesor, if it returns true, the element is added to the current group. Otherwise a new group is made

Result for array().groupSequence()

array().groupSequence() returns a new array (ie the original array, has not changed) with subarray for each group.

Example for array().groupSequence()

Suppose following initialization:

var fn=function(a,b){return b-a===1}
var fn2=function(a,b){return typeof a===typeof b}
var testArray=[1,2,3,5,6,8,9]
var testArray2=[undefined,undefined,2,2,"a","b",{t:1},{a:2}]

var result=array(testArray).groupSequence(fn)
var result2=array(testArray2).groupSequence(fn2)

This will result in:

result===[[1,2,3],[5,6],[8,9]]
result2===[[undefined,undefined],[2,2],["a","b"],[{t:1},{a:2}]]

array().replaceNull()

The method array().replaceNull() replaces all null or undefined values with a value described by replacer

array(arr).replaceNull(replacer)

Remark: empty values (ie [/empty/,"not empty"]) are considered undefined. But there's a slight difference with explicitly defining undefined as the value.

try following code:

[1,,2].map(v=>"ok")===["ok",,"ok"]
[1,undefined,2].map(v=>"ok")===["ok","ok","ok"]

The reason for this is the implementation of map; it makes an object of the array `Object([1,,2]) and checks if the key (ie the index) exists in this object. For empty values this returns false. If someone has more information about this, feel free to contact me.

Parameters for array().replaceNull()

array().replaceNull() takes 1 parameters:

• replacer [Function or Array or ???]:replacer may come in three forms, and defines the value that any undefined, empty or null-value will be changed to.
  • replacer [Function]: is a function with parameters (currentValue and currentIndex) if a null, undefined or empty (!!! an empty value is taken into account aswell) the function get's executed and based on the curentValue and it's index the return-value will be put in the array.
  • replacer [Array]: if a null, undefined or empty is encountered the currentValue get's changed by the value of the replacerArray at the given index.
  • replacer [anything else]: all the null's, undefined or empty values are replaced by the replacer-value itself

Result for array().replaceNull()

array().replaceNull() returns a new array (ie the original array, has not changed) with the correct result.

Example for array().replaceNull()

Suppose following initialization:

var testArray=array(["ok","null",null,undefined,"test",false,3,,"end"]);
var replacerV="replaced";
var replacerA=["replaced0","replaced1","replaced2","replaced3","replaced4","replaced5"];
var replacerF=function(value,i){
 if (value===null){
  return "replacednull_"+i;
 }
 else if (typeof value==="undefined"){
  return "replacedundef_"+i;
 }
 else{
  return "????"
 }
};

var resultV=array(testArray).replaceNull(replacerV)
var resultA=array(testArray).replaceNull(replacerA)
var resultF=array(testArray).replaceNull(replacerF)

This will result in:

resultV===["ok","null","replaced","replaced","test",false,3,"replaced","end"]
resultA===["ok","null","replaced2","replaced3","test",false,3,undefined,"end"]
resultF===["ok","null","replacednull_2","replacedundef_3","test",false,3,"replacedundef_7","end"]

DevDependencies

• csv2readme: read csv file with fixed format and parse a readme markdown file
• rimraf: A deep deletion module for node (like rm -rf)
• rollup: Next-generation ES6 module bundler
• tape: tap-producing test harness for node and browsers

License

This module is licensed under the terms of GPL-3.0.