的Javascript的forEach返回值插值到字符串

stack_html += "<div class='co-stack-layer-title'>Application and Data" + 
         "<div class='row'>" + 
          response['Application and Data'].forEach(generateStackItem) + 
         "</div>" + 
         "</div>"; 
stack_html += "<div class='co-stack-layer-title'>Business Tools" + 
         "<div class='row'>" + 
          response['Business Tools'].forEach(generateStackItem) + 
         "</div>" + 
         "</div>"; 
stack_html += "<div class='co-stack-layer-title'>DevOps" + 
         "<div class='row'>" + 
          response['DevOps'].forEach(generateStackItem) + 
         "</div>" + 
         "</div>"; 
stack_html += "<div class='co-stack-layer-title'>Utilities" + 
         "<div class='row'>" + 
          response['Utilities'].forEach(generateStackItem) + 
         "</div>" + 
         "</div>"; 

function generateStackItem(element, index, array) { 
    var stack_item_html = ""; 
    stack_item_html += "<div class='co-service'>" + 
        "<a href='" + element['canonical_url'] + "' class='each-service hint hint--top' data-hint='" + element['name'] + "' data-align='left'>" + 
         "<img src='" + element['image_url'] + "'>" + 
        "</a>" + 
        "</div>"; 

    console.log(stack_item_html); 
    return stack_item_html;      
}

我試圖用一個forEach迭代JavaScript對象上，似乎我不能插值的返回值到字符串相加。的Javascript的forEach返回值插值到字符串

<div class='co-stack-layer-title'>Application and Data<div class='row'>undefined</div></div><div class='co-stack-layer-title'>Business Tools<div class='row'>undefined</div></div><div class='co-stack-layer-title'>DevOps<div class='row'>undefined</div></div><div class='co-stack-layer-title'>Utilities<div class='row'>undefined</div></div>

來源

2015-10-22 Sergio Tapia

您使用的回覆如何？你想用generateStackItem做什麼？ – Danmoreng

forEach返回undefined。使用map + join。

"abc" + response['Utilities'].map(generateStackItem).join("") + "def";

來源

2015-10-22 16:00:02 Halcyon

真棒謝謝 –

map + join = [reduce]（https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Reduce），稍微調整一下回調。 – James

map + join！= reduce。在加入的情況下，你可以將你的作品合適地粘合在一起，減少難度。儘管這裏並不重要。 – Halcyon

當您的數組是空的，forEach函數將返回undefined，e.g.you會得到一個undefined當你調用forEach這樣[].forEach(generateStackItem)，因此請確保response['Application and Data']是一個空數組。

來源

2015-10-22 16:14:25 Wahson

的Javascript的forEach返回值插值到字符串

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