数组字段为空时，替换值无法正常工作 [英] Replacing values doesn't work ok when array field is empty

问题描述

我有此代码:

$('#myTextArea').val($('#myTextArea').val().replace(linesText[4] + '\n', ""));

，它工作正常.问题是在这种情况下:

and it works fine. The problem is in this case:

$('#myTextArea').val() = "\n\n33333333333\n\n\n"

和linesText是此数组:

and linesText is this array:

0: ""
1: ""
2: "33333333333"
3: ""
4: ""
5: ""

我想发生的事情:$('#myTextArea').val()变成"\ n \ n33333333333 \ n \ n".

What I want to happen: $('#myTextArea').val() to become "\n\n33333333333\n\n".

会发生什么:

$('#myTextArea').val()

成为

"\n33333333333\n\n".

之所以会发生这种情况，是因为我实际上用"替换了" +"\ n"，并且使用了第一个"\ n".我想拿第四. 如何解决这个问题? 当linesText的字段不为空时，此方法有效.

This happens because I actually replace "" + "\n" with "" and it takes the first "\n". I want to take the fourth. How to fix this? This works when linesText's fields aren't empty.

推荐答案

我做了一个可能需要改进的小功能，但是似乎可以用:

i've made a small function that probably needs improvement, but seems to work:

var ok = "\n\n33333333333\n\n\n";

function replaceSymbol(dataStr, toFind, elemPos) {
    var spacing = toFind.length;
    var indexToReplace = 0 - spacing;
    var curString;
    for (var i = 0; i < elemPos; i++) {
        curString = dataStr.substr(indexToReplace + spacing);
        if (curString.indexOf(toFind) == -1) 
            return false;
        indexToReplace = indexToReplace + curString.indexOf(toFind) + spacing;
    }
    return dataStr.substr(0, indexToReplace) + dataStr.substr(indexToReplace + spacing);
}

replaceSymbol(ok, '\n', 4);

此函数要求输入3个参数，即字符串(ok)，要替换的符号('\ n')和位置(在本例中为该符号的第4次出现)

this function ask for 3 parameters, the string (ok), the symbol to replace ('\n') and the position (in this case the 4th occurence of the symbol)

如果该函数在该位置之前/之后找不到符号，则该函数返回false，而如果一切正常，该函数将返回不包含元素在第N个位置的字符串

if the function can't find the symbol before/in the position, the function return false, while if all is ok the function will return the string without the element in Nth position

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