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If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked. JavaScript provides three different value-comparison operations: Which operation you choose depends on what sort of comparison you are looking to perform. Briefly: They correspond to three of four equality algorithms in JavaScript: Note that the distinction between these all have to do with their handling of primitives; none of them compares whether the parameters are conceptually similar in structure. For any non-primitive objects Strict equality compares two values for equality. Neither value is implicitly converted to some other value before being compared. If the values have different types, the values are considered unequal. If the values have the same type, are not numbers, and have the same
value, they're considered equal. Finally, if both values are numbers, they're considered equal if they're both not
Strict equality is almost always the correct comparison operation to use. For all values except numbers, it uses the obvious semantics: a value is only equal to itself. For numbers it uses slightly different semantics to gloss over two different edge cases. The first is that floating
point zero is either positively or negatively signed. This is useful in representing certain mathematical solutions, but as most situations don't care about the difference between Besides
Loose equality using ==Loose equality is symmetric:
Traditionally, and according to ECMAScript, all primitives and objects are loosely unequal to In most cases, using loose equality is discouraged. The result of a comparison using strict equality is easier to predict, and may evaluate more quickly due to the lack of type coercion. The following example demonstrates loose equality comparisons involving the number primitive
Loose equality is only used
by the Same-value equality using Object.is()Same-value equality determines whether two values are functionally identical in all contexts. (This use case demonstrates an instance of the Liskov substitution principle.) One instance occurs when an attempt is made to mutate an immutable property:
Same-value equality is provided by the Same-value-zero equalitySimilar to same-value equality, but +0 and -0 are considered equal. Same-value-zero equality is not exposed as a JavaScript API, but can be implemented with custom code:
Same-value-zero only differs from strict equality by treating Comparing equality methodsPeople often compare double equals and triple equals by saying one is an "enhanced" version of the other. For example, double equals could be said as an extended version of triple
equals, because the former does everything that the latter does, but with type conversion on its operands — for example, However, this way of thinking implies that the equality comparisons form a one-dimensional "spectrum" where "totally strict" lies on one end and "totally loose"
lies on the other. This model falls short with When to use Object.is() versus triple equalsIn general, the only time
Here's a non-exhaustive list of built-in methods and operators that might cause a distinction between - (unary negation)Consider the following example:
If Math.atan2 ,
Math.ceil , Math.pow , Math.round In some cases, it's possible for a Math.floor , Math.max , Math.min ,
Math.sin , Math.sqrt , Math.tan It's possible to get a ~ , << , >>
Each of these operators uses the ToInt32 algorithm internally. Since there is only one representation for 0 in the internal 32-bit integer type, Relying on Caveat: Object.is() and NaNThe
See alsoWhich three 3 roles are typically found in an information security organization?The three primary tenants to support this are confidentiality, integrity and availability. This is called the CIA triad, or the three pillars or principles of information security. Confidentiality is the principle that information should only be available to those with the proper authorization to that data.
Which of these is the best definition of cybersecurity?Cyber security is the application of technologies, processes, and controls to protect systems, networks, programs, devices and data from cyber attacks.
Which of the following can be considered as an information security incident?An InfoSec incident is the unauthorized access, use, disclosure, data breach, modification or destruction of information. It can be a suspected, attempted, successful, or imminent threat of that unauthorized access.
Which of the following defines a security threat?Defining a security threat
A potential for violation of security, which exists when there is an entity, circumstance, capability, action, or event that could cause harm. An event or condition that has the potential for causing asset loss and the undesirable consequences or impact from such loss.
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