What does js memory leak mean? Introduction to js memory leaks

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Memory leak# means that a piece of allocated memory cannot be used or recycled until the browser process ends.

The garbage collector periodically scans objects and counts the number of other objects that have references to each object. If an object has 0 references (no other objects refer to it), or the only reference to the object is circular, then the object's memory can be reclaimed.

If the first parameter of setTimeout uses a string instead of a function, it will cause a memory leak.

Closure, console log, loop (when two objects refer to each other and retain each other, a loop will occur)

Method to release memory: assign value to "null

Causes of memory leaks:

1. Memory leaks caused by unexpected global variables

Cause: Global variables will not be recycled.

Solution: Use Strict mode avoids

2. Memory leaks caused by closures

Reason: Closures can maintain local variables within the function so that they cannot be released.

Solution: The event handler function is defined externally, contacts the closure, or deletes the reference to the DOM in the external function that defines the event handler function.

3. DOM element references that are not cleaned

Cause: Although deleted elsewhere, the DOM reference still exists in the object.

Solution: Manual deletion

4. Forgotten timer or callback

Cause: Timing There is a reference to the DOM in the device. Even if the DOM is deleted, the timer is still there, so the DOM is still in the memory.

Solution: Manually delete the timer and DOM

5. Sub-elements There is a memory leak caused by reference

Reason: when the ul li in p gets this p, it will indirectly reference a certain obtained li. At this time, because p indirectly refers to li, even if li is cleared, it is still in the memory. , and as long as li is not deleted, its parent element will not be deleted.

Solution: Manually delete the situation

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