Javascript column-formatted string

Although I've worked with it in C and Java, I forget the basic output method for getting placeholders to make columns on a text output:

Oakenshie开发者_开发知识库ld     Thorin
Baggins         Bilbo
Gray, the       Gandalf

Then, once this function is known, where can I find a standalone library to do it in Javascript?

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Do you mean sprintf()'s width format specifier (e.g. %20d)? If so, Javascript sprintf is indeed your answer.

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How I do it

var data = [["Oakenshield", "Thorin"], ["Baggins", "Bilbo"], ["Gray, the", "Gandalf"]];
var display = document.querySelectorAll("[id^=display]");

Library:
    var pads = (x,len,z=" ") => (x + Array(len).fill(z).join("")).slice(0,len);
    var padn = (x,len,z=0,base) => 
        (Array(len).fill(z).join("") + x.toString(base)).slice(-len);
    var sprintf = (str, ...argv) => !argv.length ? str : 
        sprintf(str = str.replace(sprintf.token||"$", argv.shift()), ...argv);

Demo1:
    var f = item => sprintf("$$\n", pads(item[0],16), pads(item[1],16));
    display[0].innerHTML = data.map(f).join("");

Demo2:
    var f = (item,i) => sprintf("$ $ $ $\n", 
        padn(i,4), padn(item[1],6," "), pads(item[0],9), padn(i,4,0,2));
    display[1].innerHTML = data.map(f).join("");

<b>Demo 1:</b><pre id="display1" style="margin-top: 0"></pre>
<b>Demo 2:</b><pre id="display2" style="margin-top: 0"></pre>