StringBuilder for Node.js

An easy and fast in-memory string builder for Node.js.

Code Example

constStringBuilder=require("node-stringbuilder");constsb=newStringBuilder("Hi");sb.appendLine(",").append("This is a simple example demonstrating how to use this module.");console.log(sb.toString());// Hi,// This is a simple example demonstrating how to use this module.sb.insert("Text can be added into any position of this builder.");sb.replace(53,118,"Or replace the existing text.");console.log(sb.toString());// Text can be added into any position of this builder.HOr replace the existing text.sb.deleteCharAt(52).insert(52," ");console.log(sb.toString());// Text can be added into any position of this builder. Or replace the existing text.sb.toLowerCase().replaceAll("text","string");console.log(sb.toString());// string can be added into any position of this builder. or replace the existing string.console.log(sb.clone().reverse().toString());// .gnirts gnitsixe eht ecalper ro .redliub siht fo noitisop yna otni dedda eb nac gnirtsconsole.log(sb.toString(0,19));// string can be addedconsole.log(sb.length());// 86console.log(sb.count());// 15console.log(sb.indexOf("is"));// Uint32Array [ 43, 72 ]console.log(sb.indexOfSkip("is"));// Uint32Array [ 43, 72 ]console.log(sb.lastIndexOf("is"));// Uint32Array [ 72, 43 ]console.log(sb.indexOfRegExp(/is/g));// { index: [ 43, 72 ], lastIndex: [ 45, 74 ] }console.log(sb.repeat().indexOf("is"));// Uint32Array [ 43, 72, 129, 158 ]sb.substring(11,37);console.log(sb.toString());// be added into any positionconsole.log(sb.equalsIgnoreCase("be Added into Any position"));// trueconsole.log(sb.toBuffer());// UTF-8 encoded

Features

• Implemented with N-API.
• Operating strings in a scalable buffer.
• Multiple types of data are allowed to input.
  • Strings
  • Buffers(UTF-8 encoded)
  • Instances of this StringBuilder module
  • ReadStream(to read file)
  • Numbers, booleans, other objects
• Fast string search algorithm(Boyer-Moore-MagicLen)
• Clonable

Usage

Initiaiizing

Import this module by using require function.

constStringBuilder=require('node-stringbuilder');

Use new operator or from function to create a StringBuilder instance.

constsb1=newStringBuilder();// or constsb2=StringBuilder.from();

When creating an instance of StringBuilder, you can initialize the text and capacity.

constsb=StringBuilder.from("First",4096);

By default, a block of buffer space used by StringBuilder is 128 characters. The space of the buffer can be expanded or shrinked by blocks.

// To expandconstnewCapacity=65536;sb.expandCapacity(newCapacity);// To shrinksb.shrinkCapacity();

If some text are added into StringBuilder, StringBuilder will check its space. And if the space is too small, it will re-alloc a bigger one automatically. This re-allocation has overheads, if it does this frequently, your program may be slowed down. Therefore, if you can predict the length of your text, please set the capacity when creating a StringBuilder instance.

Append

Concat text.

sb.append("string").append(123).append(false).append(fs.createReadStream(path));

Add a new line after append.

sb.appendLine("string");

Append text repeatedly.

sb.appendRepeat("string",3);

Append a file asynchronizely.

awaitsb.appendReadStream(fs.createReadStream(path));

Insert

Insert text to any position.

sb.insert("string");// To the head.sb.insert(5,"string");

Replace

Replace text to the position in a range of index.

sb.replace(4,15,"string");

Replace existing substrings to another.

sb.replacePattern("old","new");sb.replacePattern("old","new",offset,limit);

Replace all existing substrings to another.

sb.replaceAll("old","new");

Delete

Delete text from a range of index.

sb.delete(4,15);

Delete a character at a index.

sb.deleteCharAt(4);

Clear all text, but preserve the capacity.

sb.clear();

Substring

Reserve text in a range of index.

sb.substring(1,5);// input the start and end index

sb.substr(1,5);// input the start index and length

Reverse

Reverse text.

sb.reverse();

Upper/Lower Case

Convert text to upper or lower case.

sb.upperCase();sb.lowerCase();

Trim

Remove any leading and trailing whitespace.

sb.trim();

Repeat

Repeat current text for specific count.

sb.repeat(1);

Expand Capacity

Expand the capacity of this StringBuilder.

sb.expandCapacity(4096).append("string");

Expand and get the updated capacity,

constcapacity=sb.expandCapacity(4096,true);

Shrink Capacity

Shrink the capacity of this StringBuilder.

sb.shrinkCapacity().clone().append("string");

Shrink and get the updated capacity,

constcapacity=sb.shrinkCapacity(true);

Get Current Text Length

To get the length of this StringBuilder,

constlength=sb.length();

Get Current Capacity

To get the length of this StringBuilder,

constcapacity=sb.capacity();

Count the words

To count the words,

constwords=sb.count();

Build String

Build a string of a specific range of index.

conststr=sb.toString(4,10);

Build a UTF-8 buffer of a specific range of index.

constbuffer=sb.toBuffer(4,10);

To get the full text,

consttext=sb.toString();constbuffer=sb.toBuffer();

To get one character at a specific index,

constc=sb.charAt(4);

Search String

Search substrings from the head,

constindexArray=sb.indexOf("string");constindexArray2=sb.indexOf("string",offset,limit);

Search substrings from the head by using RegExp,

varindexArray=sb.indexOf(/string/g);

Search substrings from the end,

constindexArray=sb.lastIndexOf("string");

Equals

Determine whether the two strings are the same.

constequal=sb.equals("string");

To ignore the case of letters,

constequal=sb.equalsIgnoreCase("string");

Determine whether it starts or ends with a specific pattern.

conststart=sb.startsWith("string");constend=sb.endsWith("string");

RegExp is not supported in startsWith and endsWith methods.

Clone

Clone this StringBuilder.

constnewSB=sb.clone();

Tests

To run the test suite, first install the dependencies, then run npm test:

npm install
npm test

Benchmark

To run the benchmark suite, first install the dependencies, then run npm run benchmark:

npm install
npm run benchmark

Here is my result,

Append
- 43 milliseconds
✓ Natively append text 1000000 times (43ms)
- 567 milliseconds
✓ Use StringBuilder to append text 1000000 times (567ms)
- 1278 milliseconds
✓ Use StringBuilder to insert text 1000000 times at the end (1287ms)
- 17 milliseconds
✓ Use StringBuilder to append text 1000000 times repeatly
Insert
- 92 milliseconds
✓ Natively insert text 10000 times (92ms)
- 10 milliseconds
✓ Use StringBuilder to insert text 10000 times
Delete
- 1427 milliseconds
✓ Natively delete text 5000 times (1429ms)
- 87 milliseconds
✓ Use StringBuilder to delete text 5000 times (88ms)
Replace
- 1511 milliseconds
✓ Natively replace text 5000 times (1513ms)
- 85 milliseconds
✓ Use StringBuilder to replace text 5000 times (86ms)
Replace Pattern
- 37 milliseconds
✓ Natively replace text with the same length by using a RegExp pattern
- 20 milliseconds
✓ Use StringBuilder to replace text with the same length by using a pattern
- 35 milliseconds
✓ Natively replace text by using a RegExp pattern
- 29 milliseconds
✓ Use StringBuilder to replace text by using a pattern
Equals
- 2 milliseconds
✓ Natively check the equal 50000 times
- 13 milliseconds
✓ Use StringBuilder to check the equal 50000 times
EqualsIgnoreCase
- 21 milliseconds
✓ Natively check the equal 50000 times
- 19 milliseconds
✓ Use StringBuilder to check the equal 50000 times
IndexOf
- 65 milliseconds
✓ Natively search text (65ms)
- 2 milliseconds
✓ Use StringBuilder to search text
Reverse
- 516 milliseconds
✓ Natively reverse text (516ms)
- 14 milliseconds
✓ Use StringBuilder to reverse text

According to the result of benchmark, if you just want to append a few different strings, please append them by using native operator + instead of this module.

License

MIT