如何摆脱第一个未定义

Question

Is there no easier way to get rid of the first element of undefined than this, by checking in the loops it isn't the first element?

    var text;

    for (d=0; d<json_nya_svar.length; d++){
        for (c=0; c<json_nya_svar[d].length; c++) {
            if (c==0 && d==0) text=json_nya_svar[d][c] + ";";
            else text += json_nya_svar[d][c] + ";";}
    text += "\r\n";
    }

Answer 1

Just give text an initial value:

var text = '';

Also, bear in mind that your loop variables are global, which can lead to various problems in the long run. Don't forget to add var before their declaration:

var text = '';
var json_nya_svar = [[1, 2, 3], [4, 5, 6]];

for (var d=0; d<json_nya_svar.length; d++){
    for (var c=0; c<json_nya_svar[d].length; c++) {
        text += json_nya_svar[d][c] + ";";
    }
    text += "\r\n";
}

console.log(text);