String Change Detector

This module provides a utility that helps generate granular changes to a string. The StringChangeDetector tracks the current / last known value of the string. After a single edit, the new value can be passed to the StringChangeDetector and the detector will determine the changed made to the string can execute callbacks that communicated them in terms of discrete modifications.

Unlike a more generalized diff, the utility assumes that the new and old values differ by only one single edit. This allows the logic to be more performant than a regular diff algorithm.

Installation

npm install --save @string-change-detector or npm install --save-dev @convergence/string-change-detector

Example Usage

const detector = new StringChangeDetector({
  value: "Hello World",
  onInsert: function(index, value) {
    console.log("'" + value + "' was inserted at index " + index);
    console.log("The value is now: '" + detector.getValue() + "'");
  }, onRemove: function(index, length) {
    console.log(length + " characters were removed at index " + index);
    console.log("The value is now: '" + detector.getValue() + "'");
  }
});

detector.processNewValue("Hello Jim");

Outputs:

5 characters were removed at index 6
The value is now: 'Hello '
'Jim' was inserted at index 6
The value is now: 'Hello Jim'

API

constructor(options)

Constructs a new StringChangeDetector.

insertText(index, value)

Updates the current value by inserting characters at the specified index.

removeText(index, length)

Removes the specified number of characters at the specified index.

setValue(value)

Sets the current value.

getValue()

Gets the current value of the string.

processNewValue(newValue)

Processes a new string that is the result of a single modification from the current value. Will fire the onInsert and onRemove callbacks as appropriate.