What is call by value in javascript
Call by Value: Suppose there is a variable named “a”. Now, we store a primitive value(boolean, integer, float, etc) in the variable “a”. Show Let us store an integer value in “a”, Let a=5. Now the variable “a” stores 5 and has an address location where that primitive value sits in memory. Now, suppose we copy the value of “a” in “b” by assignment (a=b). Now, “b” points to a new location in memory, containing the same data as variable “a”. Thus, a=b=5 but both points to separate locations in memory. This approach is called call by value where 2 variables become the same by copying the value but in 2 separate spots in the memory. Features of call by value:
Example: JavaScript
Output: “b” was just a copy of “a”. It has its own space in memory. When we change “a” it does not have any impact on the value of “b”. By value Call by reference: Let’s say, we have an object stored in the variable “a”. The variable stores the location or the address where the object lives. Now we set b=a. Now that new variable “b” instead of pointing to a new location in the memory, points to the same location where “a” does. No new object is created, no copy is created. Both the variables point to the same object. This is like having 2 names. This is call by reference. It behaves quite differently from by value. All objects interact by reference. Features of By reference:
Example: Over here, when we set d=c, “d” points to the same location in memory where “c” does. At first, we have a name-value pair stored in “c”. Now when we change a property using “c”, it changes the property in “d” also because both point to the same object. Changes in one it affects. Javascript
Output: By reference Difference between call by value and call by reference:
What is call by value with example?The call by value method of passing arguments to a function copies the actual value of an argument into the formal parameter of the function. In this case, changes made to the parameter inside the function have no effect on the argument. By default, C programming uses call by value to pass arguments.
What is call by value?Call By Value: In this parameter passing method, values of actual parameters are copied to function's formal parameters and the two types of parameters are stored in different memory locations. So any changes made inside functions are not reflected in actual parameters of the caller.
What is call by reference and call by value JS?In Call by value, a copy of the variable is passed whereas in Call by reference, a variable itself is passed. In Call by value, actual and formal arguments will be created in different memory locations whereas in Call by reference, actual and formal arguments will be created in the same memory location.
Is JavaScript by reference or by value?In JavaScript, all function arguments are always passed by value. It means that JavaScript copies the values of the variables into the function arguments. Any changes that you make to the arguments inside the function do not reflect the passing variables outside of the function.
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