JSVAL_IS_NULL 编辑

Deprecated since JavaScript api32
This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

Determine if a given jsval is null.

Syntax

JSVAL_IS_NULL(v)

Description

JSVAL_IS_NULL(v) is true if v is JSVAL_NULL, which is the JavaScript null value.

(Note: JSVAL_IS_OBJECT(JSVAL_NULL) is also true.)

Example

The following code snippet illustrates how a JavaScript variable, MyItem, is conditionally tested in an if statement to see if it contains a null value.

if (JSVAL_IS_NULL(MyItem)) {
    ...
}

See Also

• bug 952650