Precautions for using setTimeout in js, jssettimeout

Precautions for using setTimeout in js, jssettimeout

SetTimeout is frequently used in js. The most common is timer.

SetTimeout usage is simple var r = setTimeout (func, 1000 );

First, it uses the return value to clear setTimeout and clearTimeout (r)

SetTimeout call Method

SetTimeout (func, 1000 );

SetTimeout ("func ()", 1000 );

SetTimeout (function () {func ()}, 1000 );

In the first method, note that this points to the problem.

Var A = function ()

{

This. key = 1;

This. valuesss = 1;

This. func = function ()

{

Alert (this. valuesss );

}

}

Var a = new ();

SetTimeout (a. func, 1000 );

At this time, the system will surely prompt that the valuesss cannot be found, because this points to the window

Window. setTimeout = function (func, timer ){}