// iterate through all pages in the document
for (var i = 0; i < this.numPages; i++) {
var page = this.getPageNth(i);
var contentStream = page.contents;
// iterate through each text object on the page
for (var j = 0; j < contentStream.length; j++) {
var element = contentStream[j];
// check if the element is a text object
if (element instanceof TextObject) {
var textState = element.getTextState();
var text = element.text;
// iterate through each character in the text object
for (var k = 0; k < text.length; k++) {
var char = text.charAt(k);
// check if the character is a letter
if (/[a-zA-Z]/.test(char)) {
// create a new path object for the character
var path = new Path();
path.strokeColor = null;
path.fillColor = textState.fillColor;
path.strokeWidth = textState.lineWidth;
path.strokeCap = 'round';
path.strokeJoin = 'round';
// convert the character to a vector path
var glyph = fontToGlyph(char, textState.fontName);
var pathData = glyphToPath(glyph);
path.pathData = pathData;
// replace the character in the text object with the path object
var charWidth = glyph.width * textState.fontSize / 1000;
var charHeight = textState.fontSize;
var charX = textState.transform[4] + textState.charSpace * k;
var charY = textState.transform[5];
var charMatrix = new Matrix(charWidth, 0, 0, charHeight, charX, charY);
element.removeChild(k);
element.insertChild(k, path);
path.matrix = charMatrix;
}
}
}
}
}
// convert a character to its glyph representation
function fontToGlyph(char, fontName) {
var font = fontName ? fontName : 'Helvetica';
var glyph = fontToUnicode(font, char.charCodeAt(0));
if (glyph === null) {
font = 'Helvetica';
glyph = fontToUnicode(font, char.charCodeAt(0));
}
return glyph;
}
// convert a glyph to its vector path representation
function glyphToPath(glyph) {
var pathData = '';
var paths = glyph.path;
for (var i = 0; i < paths.length; i++) {
var points = paths[i].points;
var type = paths[i].type;
pathData += type;
for (var j = 0; j < points.length; j++) {
var x = points[j].x;
var y = points[j].y;
pathData += x + ',' + y + ' ';
}
}
return pathData.trim();
}
```
The code works by iterating through each page in the PDF document and then iterating through each text object on the page. For each text object, the code iterates through each character in the text and checks if it is a letter. If the character is a letter, the code creates a new vector path object for the character and replaces the character in the text object with the path object. If the character is a digit, it is left as text.
The `fontToGlyph` function converts a character to its glyph representation for a given font. The `glyphToPath` function converts a glyph to its vector path representation.