Code
var choosed = null; // 1
EventUtil.addHandler(lists, "click", cancel.bind(null, choosed)); // 2
EventUtil.addHandler(delSure, "click", delNote.bind(null, choosed)); // 3problem description
- the first line of code is used to save the button choosed being clicked as a global variable
- every time the second line of code is clicked first, then the value of choosed is changed in the cancel function, pointing to the dom element being clicked,
- when the third line of code is clicked, you need to get the value of choosed and find that choosed = null,
expected results
when the third line of code executes, choosed should be equal to the value changed by the second line of code, not null
debugging
suspects that how do you tell the difference between the original value and the reference value? , choosed = null is not the original value, so it is changed to choosed = {} , and the result is still wrong, so refer to the netizen"s answer and change the code to: choosed = {} / / 1 when the second line changes to: choosed.a =", as a result choosed.a can be obtained on the third line, obviously this is a reference value, so why choosed = null; or choosed = {} < / code
question
choosed = null; or choosed = {} , which I take as the original