Question

我是新手，所以我想我错过了一些简单的东西。 foor循环工作正常，但在其中我得到一个未定义的变量

 var categories_info = ["historia","excelencia","arte","social","instalaciones","padres","familia"];
for ( var i = 0; i < categories_info.length; i++) {
  $("#showMe-"+categories_info[i]).click(function(){
    $(".info."+categories_info.[i]).addClass("info-show");
    console.log(".info."+categories_info[i]); //debug is undefinded
  });
};

Answer 1

你需要创建一个像

这样的闭包

var categories_info = ["historia", "excelencia", "arte", "social", "instalaciones", "padres", "familia"];
for (var i = 0; i < categories_info.length; i++) {
    (function(i) {
        $("#showMe-" + categories_info[i]).click(function() {
            $(".info." + categories_info[i]).addClass("info-show");
            console.log(".info." + categories_info[i]); 
        });
    })(i);
};

此方法称为IIFE

基本上，当发生实际点击时，发生的变量i对回调不可用。

但是，通过在自动执行的匿名函数中传递i，您创建了一个闭包，它将保留i并可供点击处理程序访问。

Answer 2

使用闭包。变化：

> SECDraft = read.csv("SECDraftScouting.csv", stringsAsFactors=FALSE)
> SECcorpus = Corpus(VectorSource(SECDraft$Report))
> SECcorpus = tm_map(SECcorpus, tolower)
> SECcorpus = tm_map(SECcorpus, PlainTextDocument)
> SECcorpus = tm_map(SECcorpus, removePunctuation)
> SECcorpus = tm_map(SECcorpus, removeWords, c("strengths", "weaknesses", "notes", stopwords("english")))
> SECfrequencies = DocumentTermMatrix(SECcorpus)
> SECallReports = as.data.frame(as.matrix(SECfrequencies))
> wordcloud(colnames(SECallReports), colSums(SECallReports), random.order = FALSE, max.words = 200, scale=c(2, 0.25))

要：

$("#showMe-"+categories_info[i]).click(function(){
    $(".info."+categories_info.[i]).addClass("info-show");
    console.log(".info."+categories_info[i]); //debug is undefinded
});

在for循环中点击函数内部获取未定义的数组

2 个答案: