JavaScript是否有像“range（）”这样的方法？在提供的范围内生成一个范围？ [英] Does JavaScript have a method like "range()" to generate a range within the supplied bounds?

问题描述

在PHP中，你可以做...

In PHP, you can do...

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

也就是说，有通过传递上限和下限，可以让你获得一系列数字或字符的函数。

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

本机有什么内置的JavaScript吗？如果没有，我将如何实现它？

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

推荐答案

它适用于字符和数字，可选步骤前进或后退。

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 < 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;

}

jsFiddle 。

如果要扩充原生类型，请将其分配给数组.range 。

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 < 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;

}

console.log(range("A", "Z", 1));
console.log(range("Z", "A", 1));
console.log(range("A", "Z", 3));


console.log(range(0, 25, 1));

console.log(range(0, 25, 5));
console.log(range(20, 5, 5));

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