CODEWITHSUNDEEP
javascript
Abhishek Agrawal
Abhishek Agrawal

Reputation: 73

Why the following JavaScript code is not valid?

When the following code is executed in chrome console

let a, b, c;
b = 2;
a = b+1 = c = 2+3;

It says an error 'Invalid left-hand side assignment' for the last statement. But when we execute the below-given code it accepts it and does not show any error. 

let a, b, c;
a = b = c = 2+3;

assignment '=' is an operator so according to operator precedence in javascript, it should work fine. what do you guys think, what is the problem?

Upvotes: 1

Views: 92

Answers (3)

Jonas Wilms
Jonas Wilms

Reputation: 138257

You just need some parenthesis to make it clear what you mean:

 a = 1 + (b = c = 2+3);

Upvotes: 0

ykaner
ykaner

Reputation: 1840

the = operator calculate first the right side and require the left side to be lvalue.

In your second example for every assignment operator the left side is always a variable, so it works fine. but in the first example:

let a, b, c;

b = 2;

a = b+1 = c = 2+3;

you trying to assign 5 into b+1, its simply not a variable.

Upvotes: 1

Garret
Garret

Reputation: 140

for the first code you would need to do

let a,b,c;
b=2;
a=b+1;
c=5;

doing

a=b=c=2+3

works because you arent altering a value to the left of the last equal

Upvotes: 1

Related Questions