Question

嗨，我从以下JavaScript代码中获取未定义的内容。我想要一个调试JavaScript的工具，Webstorm是最好的吗？

//input
var inputArray = [1, 2, 3, 4, 5, 5, 5, 6, 66];
var searchValue = 2;
//output
var arrayLength = inputArray.length;
var arrayCurrent = inputArray;
var currentIndex = arrayLength;
function binarySearch() {
    currentIndex = Math.floor(arrayCurrent.length / 2);
    if (searchValue == arrayCurrent[currentIndex]) {
        var x=currentIndex;
        return x;
    } else if (searchValue > arrayCurrent[currentIndex]) {
        arrayCurrent = arrayCurrent.slice(currentIndex + 1);
        binarySearch();//recursive call

    } else if (searchValue < arrayCurrent[currentIndex]) {
        arrayCurrent = arrayCurrent.slice(0, currentIndex - 1);
        binarySearch();//recursive call
    }

}
var found=binarySearch();
console.log("the index of the searched value is: " + found);

Console output:
the index of the searched value is: undefined

Answer 1

只有在函数调用自身时才会发生递归。但在这种情况下，你可以使用一个循环。

我在Oliver Caldwell's blog上找到了以下示例：

＆＃13;

var inputArray = [1, 2, 3, 4, 5, 5, 5, 6, 66];
var searchValue = 6;

function binarySearch(searchValue, inputArray) {
    var minIndex = 0,
        maxIndex = inputArray.length - 1,
        currentIndex,
        currentElement;
 
    while (minIndex <= maxIndex) {
        currentIndex = (minIndex + maxIndex) / 2 | 0;
        currentElement = inputArray[currentIndex];
 
        if (currentElement < searchValue)
            minIndex = currentIndex + 1;
        else if (currentElement > searchValue)
            maxIndex = currentIndex - 1;
        else
            return currentIndex;
    }
 
    return -1;
}

var found = binarySearch(searchValue, inputArray);
console.log("The index of the searched value is: " + found);

＆＃13;

二进制搜索递归函数在JavaScript中返回undefined？

1 个答案: