javascript for 循环 - 如何获取 [i] 之前的文本

Question

我正在尝试创建一个解析器来将坐标数据解析为 json。数据位于简单 x,y 格式的文本文件中。我正在尝试获取 [i] 之前的文本，可以使用 .split() 吗？

代码:

function visualize()
{
    if(currDoc == null)
    {
        var location = window.prompt("Please enter the name of the dataset file, and make sure it is in the data directory. Current supported formats txt.");
        location = "data/" + location;
        jQuery.get(location, function(data) {
            data = data.replace(/\s/g, '');
            var length = data.length;
            var commaCount = 0;
            for(var i=0;i<length;i++)
            {
                if(data[i] == ",")
                {
                    commaCount += 1;
                    if(commaCount == 2)
                    {
                        //get text before [i]
                    }
                }
            }
        }, "text").fail(function(){ alert("File not found. Did you enter the file name correctly?") });
    }
    else
    {
        alert("A dataset is already visualized");
    }
}

Answer 1

如果您的数据以逗号分隔，例如 x1,y1,x2,y2,...,xn,yn，您可以使用 split 函数来拆分数据字符串转换为标记。然后您可以迭代它们以从输入中收集您需要的任何内容。

例如，如果您需要 x 和 y 对，您将执行以下操作:

function visualize()
{
    if(currDoc == null)
    {
        var location = window.prompt("Please enter the name of the dataset file, and make sure it is in the data directory. Current supported formats txt.");
        location = "data/" + location;
        jQuery.get(location, function(data) {
            data = data.replace(/\s/g, '');

            // split the string 'x1,y1,...,xn,yn' into tokens ['x1', 'y1', ... 'xn', 'yn']
            var tokens = data.split(',');

            // iterate over all tokens using a step of 2 (i += 2)
            // Note: if you have an odd number of tokens the last one will be ignored
            // (this is by design because you are expecting x,y pairs)
            for(var i = 1; i < tokens.length; i += 2)
            {
                // print the (x,y) pair to the console
                console.log("New pair (" + tokens[i-1] + "," + tokens[i] + ")");
            }
        }, "text").fail(function(){ alert("File not found. Did you enter the file name correctly?") });
    }
    else
    {
        alert("A dataset is already visualized");
    }
}