javascript - 如何在第一次迭代时设置一个值然后从不在 Javascript 中更改它

Question

我正在尝试实现一个研究栏来学习 Meteor、JavaScript 等……问题是我想转到与搜索匹配的第一篇文章，但说“还有 X 篇文章符合您的条件"

我试过这个:

'click .tfbutton'(event){
      var research = document.getElementById('tftextinput').value.toLowerCase();
      var nombreValide = 0;
      var lastArticlePos = 0;

      setTimeout(function(){
        $('.titreArticle').each(function(i, obj) {
          var acutal = obj.textContent.toLowerCase();
            if(acutal.includes(research)){
                nombreValide = nombreValide + 1;
                var position = obj.offsetTop;
                window.scrollTo(0,position);
                document.getElementById('tftextinput').value = "";
            }else{
               document.getElementById('tftextinput').value = "";
              console.log("We can't find an article with your criterias");
            }
        });
        console.log("There is : " + nombreValide + " articles who matchs");
      }, 20)
      },

我想在第一次迭代时设置 lastArticlePos 然后不再更改它，但仍将 1 添加到 nombreValide。

Answer 1

只需用 null 初始化它，只有当 null 时才将它设置为其他值:

'click .tfbutton'(event){
      var research = document.getElementById('tftextinput').value.toLowerCase();
      var nombreValide = 0;
      var lastArticlePos = null;

      setTimeout(function(){
        $('.titreArticle').each(function(i, obj) {
          var acutal = obj.textContent.toLowerCase();
            if(acutal.includes(research)){
                if (lastArticlePos === null) lastArticlePos = i;
                nombreValide = nombreValide + 1;
                var position = obj.offsetTop;
                window.scrollTo(0,position);
                document.getElementById('tftextinput').value = "";
            }else{
               document.getElementById('tftextinput').value = "";
              console.log("We can't find an article with your criterias");
            }
        });
        console.log("There is : " + nombreValide + " articles who matchs");
        console.log("Article position is : " + (lastArticlePos === null) ? "<No article found>" : lastArticlePos);
      }, 20)
      },