Question

我试图使用正则表达式构造函数查找字符串中字符串字母（变量）的出现次数，但它不起作用。

function getNumberOfOccurrences()
{
    //get input from user:
    var inputWord = document.getElementById("wordInputField").value;
    inputWord = inputWord+""; // turn it into a string
    var inputLetter = document.getElementById("letterInputField").value;
    inputLetter = inputLetter+""; // turn it into a string

    if(checkInput(inputWord , inputLetter)) // other function that checks the input
    {
        var rgxInputLetter = new RegExp(inputLetter, "g"); //use regex constructor for the match function:

        var resultArray = inputWord.match(rgxInputLetter); // use match to find occurrences. match returns an array

        var occurences = resultArray.length; // length of array should be the occurrences

        if(isNaN(occurences) && occurences >= 0) // check that match function worked and an array was returned
        {
            document.getElementById("resultField").innerHTML = "There are "+occurences + " occurrences of: \""+inputLetter+"\" in the word: \""+inputWord+"\"";
        }
        else
        {
            document.getElementById("resultField").innerHTML = "There are no occurrences of: \""+inputLetter+"\" in the word: \""+inputWord+"\"";
        }



    }


}

总是给我一个错误， resultArray null 。
即使我在匹配功能之前写了 inputLetter =“a”或 inputWord =“something”。
为什么不起作用？

Answer 1

发现它确实有效，问题是最后一条条件 isNaN（出现）。
检查发生的情况是不一个数字应该加一个！标志。 -_-
所以这解决了它：
if( ! isNaN(occurences) && occurences >= 0)

正则表达式构造函数不适用于匹配字符串字

1 个答案: