Web Worker using Transferable ArrayBuffers with Float32 views to parse a tab separated value file. The first lines is expected to contain the titles. Also returns the global minimum, maximum, and average value per column.

async-tsv-parser.js

onmessage = function(e) {
    var arrayBuffers = [];
    var float32Arrays = [];
    var titles = [];
    var reader = new FileReader();
    reader.onload = function (progressEvent) {
        var before = Date.now();
        var lines = this.result.split('\n');
        var endsWithNewLine = (lines[lines.length - 1] != "");
        var statshtml = (lines.length - (endsWithNewLine ? 2 : 1)) + " samples loaded<br />";
        titles = lines[0].split('\t');
        var min = []; max = []; avg = [];
        for(var title = 0; title < titles.length; title++){
            min[title] = Number.POSITIVE_INFINITY;
            max[title] = Number.NEGATIVE_INFINITY;
            avg[title] = 0;
            arrayBuffers[title] = new ArrayBuffer((lines.length - (endsWithNewLine ? 1 : 0))*4);
            float32Arrays[title] = new Float32Array(arrayBuffers[title]);
        }
        var progress = 0;
        for (var line = 1; line < (lines.length - (endsWithNewLine ? 2 : 1)); line++) {
            var newProgress = Math.floor(100 * line / (lines.length+1));
            if(newProgress != progress){
                progress = newProgress;
                postMessage({statshtml: "parsing " + progress + "%<br/>"});
            }
            val = lines[line].split('\t');
            for(var title = 0; title < titles.length; title++){
                var v = Number(val[title]);
                if(min[title] > v){
                    min[title] = v;
                }
                if(max[title] < v){
                    max[title] = v;
                }
                if(avg[title] == undefined){
                    avg[title] = 0;
                }
                avg[title] += v /(lines.length-1);
                float32Arrays[title][line-1] = v;
            }
        }
        var escapedTitles = [];
        for(var title = 0; title < titles.length; title++){
            var escapedTitle = titles[title].replace(/"/g,'');
            escapedTitles.push(escapedTitle);
            statshtml += escapedTitle + ": "
            + min[title] + " - " + max[title] + " ("
            + Math.round(avg[title]*10)/10 + ") <br/>";
        }
        statshtml += "parsing time [ms]: " + (Date.now() - before) + "<br/>";
        postMessage({
            statshtml: statshtml,
            stats: {min: min, max: max, avg: avg},
            titles: escapedTitles,
            arrayBuffers: arrayBuffers,
            time: Date.now()
            }, arrayBuffers);
    };
    reader.readAsText(e.data);
}