Javascript sets the ReadOnly attribute of the object (sample code)

In JS, The ReadOnly attribute is strange. directly create an object and assign the readonly attribute to this object. The following method cannot be used in HTML:
Copy codeThe Code is as follows:
Var x = document. createElement ("input ");
X. type = "text ";
X. value = "ttttt ";
X. id = "xy ";
X. readonly = "readonly ";

The created object is not read-only. The correct statement is as follows:
Copy codeThe Code is as follows:
Var x = document. createElement ("input ");
X. type = "text ";
X. value = "ttttt ";
X. id = "xy ";
X. readOnly = true;

Note This when writing JavaScript code.