59 lines
1.4 KiB
Plaintext
59 lines
1.4 KiB
Plaintext
When either the equality operator in a test for ``++null++`` or ``++undefined++``, or the logical operator that follows it is reversed, the code has the appearance of safely null-testing the object before dereferencing it. Unfortunately the effect is just the opposite - the object is null-tested and then dereferenced only if it is ``++null++``/``++undefined++``, leading to a guaranteed ``++TypeError++``.
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== Noncompliant Code Example
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[source,javascript]
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----
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if (str == null && str.length == 0) {
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console.log("String is empty");
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}
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if (str == undefined && str.length == 0) {
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console.log("String is empty");
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}
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if (str != null || str.length > 0) {
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console.log("String is not empty");
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}
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if (str != undefined || str.length > 0) {
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console.log("String is not empty");
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}
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----
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== Compliant Solution
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[source,javascript]
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----
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if (str != null && str.length == 0) {
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console.log("String is empty");
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}
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if (str != undefined && str.length == 0) {
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console.log("String is empty");
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}
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if (str == null || str.length > 0) {
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console.log("String is not empty");
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}
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if (str == undefined || str.length > 0) {
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console.log("String is not empty");
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}
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----
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ifdef::env-github,rspecator-view[]
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'''
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== Implementation Specification
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(visible only on this page)
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include::../message.adoc[]
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'''
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== Comments And Links
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(visible only on this page)
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include::comments-and-links.adoc[]
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endif::env-github,rspecator-view[]
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