javascript - 将 PHP 数组回显到 Javascript

Question

我目前正在开发一个项目，需要从数据库获取数据并将其生成为 Javascript 数组。它动态地改变图表。

我有以下 PHP 代码来获取数组。

<?php
  ini_set('memory_limit', '1024M');
  $dbconn = pg_connect(**My connection details**)
          or die('Could not connect: ' . pg_last_error());

  $county1 = $_GET['c1'];
  $county2 = $_GET['c2'];
  $county3 = "National";

  $counties = 'SELECT * FROM house_price_data_db.county_median_months where county=$1 or county=$2 or county=$3 order by county';
  $result_counties = pg_query_params($dbconn,$counties,array($county1,$county2,$county3)) or die('Query failed: ' . pg_last_error());
   $county_meds = array();

   while($r = pg_fetch_assoc($result_counties)) {
          $county_meds[] = $r;
      }
   echo("var county_med_month=".json_encode(array_values($county_meds), JSON_NUMERIC_CHECK).";");

   pg_free_result($result_counties);
   pg_close($dbconn);
?>

运行时确实返回数组。

E.g
var county_med_month=[
{"county":"Carlow","med_jan_10":165000,"med_feb_10":170000,...,"med_dec_14":null}
{"county":"Dublin","med_jan_10":285000,"med_feb_10":280000,...,"med_dec_14":null},
{"county":"National","med_jan_10":220264.31,"med_feb_10":216500,...,"med_dec_14":null}];

但是由于某些原因，当我尝试在 Javascript 代码中使用数组时，它似乎不起作用？

function county_med_chart(){
  county_1=document.getElementById("dd1_c").value;
  county_2=document.getElementById("dd2_c").value;
  var c;
  county_meds(county_1,county_2);
  for(c=0;c<county_med_month.length;c+=1){
    var a=county_med_month.c;
    if(a.county==county_1){
      med_jan_10_1=parseFloat(a.med_jan_10);
       :
      med_sep_14_1=parseFloat(a.med_sep_14);
    }
    else if(a.county==county_2){
      med_jan_10_2=parseFloat(a.med_jan_10);    
       :
      med_sep_14_2=parseFloat(a.med_sep_14);
    }
    else if(a.county=="National"){
      med_jan_10_3=parseFloat(a.med_jan_10);
       :
      med_sep_14_3=parseFloat(a.med_sep_14);
    }
  }

  var e=new google.visualization.arrayToDataTable([
    ["Year",county_1,county_2,"National"],
    ["Jan-10",med_jan_10_1,med_jan_10_2,med_jan_10_3],
    ["Feb-10",med_feb_10_1,med_feb_10_2,med_feb_10_3],
     :
    ["Aug-14",med_aug_14_1,med_aug_14_2,med_aug_14_3],
    ["Sept-14",med_sep_14_1,med_sep_14_2,med_sep_14_3],
  ]);

  var b={
    title:"House Price Index by County:",
    curveType:"function",
    is3D:true,
    legend:"top",
    width:650,
    height:280,
    hAxis: { textPosition: 'none' }};
  var d=new google.visualization.LineChart(document.getElementById("chart_div"));
  d.draw(e,b)
  }

有什么建议吗？

Answer 1

为什么在使用代码执行任何复杂的逻辑之前不尝试调试代码？

在回显数组后，请在 javascript 顶部尝试以下操作:

if(county_med_month.length > 0) 
    console.log("The array was created!, the problem was with my JavaScript code!");

顺便说一句，您不访问带有点表示法的数组值

var a=county_med_month.c;

应该是红色的

var a=county_med_month[c];