snippetjavascriptMajor

Does JavaScript have a method like "range()" to generate a range within the supplied bounds?

Submitted by: @import:stackoverflow-api·Mar 10, 2026·

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suppliedhavelikemethodthegeneratedoesrangejavascriptwithin

Problem

In PHP, you can do...

range(1, 3); // Array(1, 2, 3)
range("A", "C"); // Array("A", "B", "C")

That is, there is a function that lets you get a range of numbers or characters by passing the upper and lower bounds.

Is there anything built-in to JavaScript natively for this? If not, how would I implement it?

Solution

It works for characters and numbers, going forwards or backwards with an optional step.

var range = function(start, end, step) {
    var range = [];
    var typeofStart = typeof start;
    var typeofEnd = typeof end;

    if (step === 0) {
        throw TypeError("Step cannot be zero.");
    }

    if (typeofStart == "undefined" || typeofEnd == "undefined") {
        throw TypeError("Must pass start and end arguments.");
    } else if (typeofStart != typeofEnd) {
        throw TypeError("Start and end arguments must be of same type.");
    }

    typeof step == "undefined" && (step = 1);

    if (end  0 ? end >= start : end  0 ? end >= start : end <= start) {
            range.push(String.fromCharCode(start));
            start += step;
        }

    } else {
        throw TypeError("Only string and number types are supported");
    }

    return range;

}

jsFiddle.

If augmenting native types is your thing, then assign it to Array.range.

`var range = function(start, end, step) {
var range = [];
var typeofStart = typeof start;
var typeofEnd = typeof end;

if (step === 0) {
throw TypeError("Step cannot be zero.");
}

if (typeofStart == "undefined" || typeofEnd == "undefined") {
throw TypeError("Must pass start and end arguments.");
} else if (typeofStart != typeofEnd) {
throw TypeError("Start and end arguments must be of same type.");
}

typeof step == "undefined" && (step = 1);

if (end 0 ? end >= start : end 0 ? end >= start : end

Code Snippets

var range = function(start, end, step) {
    var range = [];
    var typeofStart = typeof start;
    var typeofEnd = typeof end;

    if (step === 0) {
        throw TypeError("Step cannot be zero.");
    }

    if (typeofStart == "undefined" || typeofEnd == "undefined") {
        throw TypeError("Must pass start and end arguments.");
    } else if (typeofStart != typeofEnd) {
        throw TypeError("Start and end arguments must be of same type.");
    }

    typeof step == "undefined" && (step = 1);

    if (end < start) {
        step = -step;
    }

    if (typeofStart == "number") {

        while (step > 0 ? end >= start : end <= start) {
            range.push(start);
            start += step;
        }

    } else if (typeofStart == "string") {

        if (start.length != 1 || end.length != 1) {
            throw TypeError("Only strings with one character are supported.");
        }

        start = start.charCodeAt(0);
        end = end.charCodeAt(0);

        while (step > 0 ? end >= start : end <= start) {
            range.push(String.fromCharCode(start));
            start += step;
        }

    } else {
        throw TypeError("Only string and number types are supported");
    }

    return range;

}

Context

Stack Overflow Q#3895478, score: 86

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