Javascript json数据未显示在js生成的表中

我在js中有一个来自php的变量，如：

var myData = <?php echo json_encode($json_array) ?>; 

从myData生成表的函数：

function generateTableHead(table, data) {
          let thead = table.createTHead();
          let row = thead.insertRow();
          for (let key of data) {
            let th = document.createElement("th");
            let text = document.createTextNode(key);
            th.appendChild(text);
            row.appendChild(th);
          }
        }

        function generateTable(table, data) {
          for (let element of data) {
            let row = table.insertRow();
            for (key in element) {
              let cell = row.insertCell();
              let text = document.createTextNode(element[key]);
              cell.appendChild(text);
            }
          }
        }


        let table = document.querySelector("table");


        let data = Object.keys(myData);


        // generate cells from values
        generateTable(table, myData);


        // create heading from keys
        generateTableHead(table, data);

---

似乎是这样的

let table=document.querySelector（“table”）返回null。是否确定在运行此查询时已创建表元素？您能确认返回空值吗？
谢谢，这个答案帮助我找到了答案。我不得不移动脚本以使其工作。
function generateTableHead(table, data) {
          let thead = table.createTHead();
          let row = thead.insertRow();
          for (let key of data) {
            let th = document.createElement("th");
            let text = document.createTextNode(key);
            th.appendChild(text);
            row.appendChild(th);
          }
        }

        function generateTable(table, data) {
          for (let element of data) {
            let row = table.insertRow();
            for (key in element) {
              let cell = row.insertCell();
              let text = document.createTextNode(element[key]);
              cell.appendChild(text);
            }
          }
        }


        let table = document.querySelector("table");


        let data = Object.keys(myData);


        // generate cells from values
        generateTable(table, myData);


        // create heading from keys
        generateTableHead(table, data);