Why am I getting 'undefined' in console?

2018-06-03 13:36:32

This question already has an answer here:

For-each over an array in JavaScript? 23 answers

A for…in loop in JavaScript loops through an object's keys, not its values. You can use Array.prototype.forEach , given support; $.each works as a fallback too, since you're using jQuery.

var textArray = ['#text1', '#text2', '#text3', '#text4',
                 '#text5', '#text6', '#text7', '#text8'];

$('#capture').click(function() {
    textArray.forEach(function (x) {
        console.log($(x).offset());
    });
});

因为i是数组中项目的索引，所以您需要使用textArray[i]来访问当前项目（如果您记录了i的值，它将显示0,1,2 ... 7）。

for (var i in textArray) {
  console.log($(textArray[i]).offset());
}

您可能想要像这样索引数组：

var textArray = ['#text1', '#text2', '#text3', '#text4',
'#text5', '#text6', '#text7', '#text8']

$('#capture').click(function() {
for (var i in textArray) {
  console.log($(textArray[i]).offset());
}
});

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