Format on save issue

[lukehaas]

The following code, when formatted on save will cause duplicate lines to be inserted:

Before:

let arr = [1,2,3];


arr.indexOf(1)

let cplxArr = [
  {id: 1},
  {id: 2},
  {id: 3}
];

cplxArr.findIndex(el => el.id === 1);

after:

let arr = [1, 2, 3];

arr.indexOf(1);
arr.indexOf(1)
let cplxArr = [{ id: 1 }, { id: 2 }, { id: 3 }];
let cplxArr = [
cplxArr.findIndex((el) => el.id === 1);

This is possibly due to the diffing code here:

ICEcoder/assets/js/icecoder.js

Lines 2180 to 2227 in 51cf24b

	editorText = difflib.stringAsLines(this.getThisCM().getValue());
	prettierText = difflib.stringAsLines(prettierVersion.formatted);
	// Create a SequenceMatcher instance that diffs the two sets of lines
	sm = new difflib.SequenceMatcher(editorText, prettierText);
	// Get the opcodes from the SequenceMatcher instance
	// Opcodes is a list of 3-tuples describing what changes should be made to the base text in order to yield the new text
	opcodes = sm.get_opcodes();
	docShift = 0;
	for (let i = 0; i < opcodes.length; i++) {
	// opcode events may be:
	// equal = do nothing for this range
	// replace = replace [1]-[2] with [3]-[4]
	// insert = replace [1]-[2] with [3]-[4]
	// delete = replace [1]-[2] with [3]-[4]
	// Params to determine if we need to set 1 or 0 shift the start line and end line
	startShift = "delete" === opcodes[i][0] && editorText.length === opcodes[i][2] ? 1 : 0;
	endShift = "replace" === opcodes[i][0] ? 1 : 0;
	if ("equal" !== opcodes[i][0]) {
	// Replace or insert
	if ("replace" === opcodes[i][0] || "insert" === opcodes[i][0]) {
	newContent = "";
	// For each of the replace/insert lines in Prettier's version
	for (let j = opcodes[i][3]; j < opcodes[i][4]; j++) {
	// Build up newContent lines and end with a new line char if not the last line in the range
	newContent += prettierText[j];
	if (j < opcodes[i][4] - 1) {
	newContent += "\n";
	}
	}
	}
	// Delete
	if ("delete" === opcodes[i][0]) {
	// Not the last line in doc, the newContent is the line after the section we're deleting in editors version
	// Else if it's the last line in doc, the content after the section we're deleting is nothing
	newContent = editorText.length > opcodes[i][2]
	? editorText[opcodes[i][2]]
	: "";
	}
	// Replace the range with newContent. The range start line and end line adjust according to
	// startShift and endShift 1/0 values plus also the +/- docShift which is how much the
	// editor document has shifted so far during replace ranges
	this.getThisCM().replaceRange(newContent, {line: opcodes[i][1] - docShift - startShift, ch: 0}, {line: opcodes[i][2] - docShift - endShift, ch: 1000000}, "+input");
	// Work out the +/- document shift based on difference between the editors last line in
	// this diff range and Prettiers last line in this diff range
	docShift = opcodes[i][2] - opcodes[i][4];