JavaScript Requires Chilkat v11.7.0+

Extract Text from a Two-Column PDF

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Demonstrates how multi-column pages are read. By default the columns are detected and each column is read top to bottom before the next ("columns": "auto"); "columns": "none" reads the full page width line by line, which interleaves the columns. The quality report tells how many columns were found. JavaScript

var success = false;

//  This example requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

//  The two-column PDF used in this example is available at two_column_article.pdf

var pdf = new CkPdf();
success = pdf.LoadFile("qa_data/pdf/two_column_article.pdf");
if (success == false) {
    console.log(pdf.LastErrorText);
    return;
}

var json = new CkJsonObject();
var jsonOut = new CkJsonObject();

//  With the default options the columns are detected, and the text of the left column
//  comes before the text of the right column.
success = pdf.ExtractText("text",json,jsonOut);
if (success == false) {
    console.log(pdf.LastErrorText);
    return;
}

console.log("Columns detected: " + jsonOut.IntOf("quality.pages[0].columns"));
console.log("Reading order: " + jsonOut.StringOf("quality.pages[0].readingOrderSource"));
console.log(jsonOut.StringOf("text"));

//  "none" switches column detection off: the page is read across its full width, line by line,
//  so each output line holds a line of the left column followed by a line of the right column.
//  This is rarely wanted, but it shows what the detection does.
json.UpdateString("columns","none");
json.UpdateString("layout","lines");
success = pdf.ExtractText("text",json,jsonOut);
if (success == false) {
    console.log(pdf.LastErrorText);
    return;
}

console.log("---- columns: none ----");
console.log(jsonOut.StringOf("text"));

//  Sample output (abbreviated):

//  Columns detected: 2
//  Reading order: visual
//  The Harbor Lighthouse, Season Two
//  
//  The harbor lighthouse was built in 1874 to mark the entrance to the inner channel. It operated continuously until 1968, ...
//  
//  The restoration society took ownership in 2021 with three goals: ...
//  ...
//  The lantern room frame was stripped, primed and repainted in the original dark green. ...
//  ...
//  ---- columns: none ----
//  The Harbor Lighthouse, Season Two
//  The harbor lighthouse was built in 1874 to The lantern room frame was stripped, primed
//  mark the entrance to the inner channel. It and repainted in the original dark green. New
//  ...