[英]can't use If - Else element exists in Javascript
I wrote a JS function to create a table in html and JS I want to click submit and after that the table to be created but I dont want the Submit button to create another table if clicked again I tried to use IF - Else statements in the function but It's not working我写了一个 JS function 在 html 和 JS 中创建一个表我想单击提交,然后创建该表,但如果再次单击我不希望提交按钮创建另一个表我尝试在function 但它不工作
code:代码:
Button:按钮:
document.getElementById("btn_submit").addEventListener("click",sizeGrid)
function function
function makeGrid(x,y) {
event.preventDefault();
if (document.getElementById('tbl') != null)
{
return;
}
else
{
var body = document.getElementById('pixelCanvas');
var tbl = document.createElement('table');
for(var i = 0; i < x; i++){
var tr = tbl.insertRow();
for(var j = 0; j<y; j++){
var td= tr.insertCell()
}
}
body.append(tbl);
paint()
}
}
HTML HTML
<h2>Design Canvas</h2>
<table id="pixelCanvas">
</table>
The table gets created two times after I click submit two times单击两次提交后,表被创建了两次
You should set the tbl
's id to 'tbl'
by tbl.id = 'tbl'
.您应该通过
tbl.id = 'tbl'
tbl
'tbl'
You are doing the check on the id of the table but never assign one.您正在检查表的 id,但从未分配一个。
function makeGrid(x,y) {
event.preventDefault();
if (document.getElementById('tbl') != null) {
return;
} else {
var body = document.getElementById('pixelCanvas');
var tbl = document.createElement('table');
tbl.id = "tbl"; // Assign the id for the check
for(var i = 0; i < x; i++){
var tr = tbl.insertRow();
for(var j = 0; j<y; j++){
var td= tr.insertCell()
}
}
body.append(tbl);
paint();
}
};
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