node util.format performance test

plusLargeData.js

#!/usr/bin/env node

var fs = require('fs');

fs.readFile('urandomStrings', 'utf8', function (err,data) {
    if (err) {
        return console.log(err);
    } else {
        console.time('concat');
        var string = '';
        string = data + 'foo';
        console.timeEnd('concat');
    }
});

plusMultipleTimes.js

#!/usr/bin/env node

console.time('concat');
var string = '';
for (var i = 0; i < 10000; i++) {
    string = 'bar' + 'foo';
}
console.timeEnd('concat');

plusSimple.js

#!/usr/bin/env node

console.time('concat');
var string = '';
string = 'bar' + 'foo';
console.timeEnd('concat');

results

[miguelfonseca@miguel-mbp ~]$ node plusMultipleTimes.js
concat: 0ms
[miguelfonseca@miguel-mbp ~]$ node utilMultipleTimes.js
concat: 18ms
[miguelfonseca@miguel-mbp ~]$ node plusLargeData.js
concat: 0ms
[miguelfonseca@miguel-mbp ~]$ node utilLargeData.js
concat: 3ms
[miguelfonseca@miguel-mbp ~]$ node plusSimple.js
concat: 0ms
[miguelfonseca@miguel-mbp ~]$ node utilSimple.js
concat: 0ms

utilLargeData.js

#!/usr/bin/env node

var fs = require('fs');
var util = require('util');

fs.readFile('urandomStrings', 'utf8', function (err,data) {
    if (err) {
        return console.log(err);
    } else {
        console.time('concat');
        var string = '';
        string = util.format('%s%s', data, 'foo');
        console.timeEnd('concat');
    }
});

utilMultipleTimes.js

#!/usr/bin/env node

var util = require('util');

console.time('concat');
var string = '';
for (var i = 0; i < 10000; i++) {
    string = util.format('%s%s', 'bar', 'foo');
}
console.timeEnd('concat');

utilSimple.js

#!/usr/bin/env node

var util = require('util');

console.time('concat');
var string = '';
string = util.format('%s%s', 'bar', 'foo');
console.timeEnd('concat');