Weak and weak JS beginners

1,

If (event. srcelement. value = "Enter the user name") event. srcelement. value = "";

If (event. srcelement. value = "") event. srcelement. value = "Enter the user name ";

The first judgment in the first line is two equal signs, and the second value is an equal sign. After the front and back are directly reversed by Ctrl + C and CTRL + V, the second line reports an error. Exercise caution when copying and pasting data.

2,

Event. srcelement. Focus ();
Event. srcelement. Select ();

At the beginning, Src was written as SCR, and the following () was not added ()

3,

<Input id = "username" onmouseover = "mover ();" onclick = "mclick ();" onblur = "mblur ();" value = "Enter the user name">

Brackets must be written for all function calls.

4. Do not copy and paste the words in the word into nodepad ++. The quotation marks in the word do not know the format. It is not in half-width English.

5. setTimeout the out is in lower case. Start a row and a rowCodeIs it true that two identical codes are followed? It's really a test of my skills! It was discovered only after being pasted into the drawing!

6. Note that B in Boolean is in uppercase.

7. var A = new array (); A. length, which has no parentheses, A. Pop (), and parentheses. What is the attribute? Do you eat it? Why is there no brackets?