Javascript Basic Tutorial Operators

Operator

First we need to know what an expression is

For example i++; a+b These are all expressions

Unary operator: can only operate one value operator, called the unary operator

increment ++ and decrement- -

Look at the following code:

The front is incremented, output 101 The rear is incremented and output 101

The front is decremented, the output is 99 The rear decrement is output 99

Note: The difference between preposition and postposition

var box=100;

//age = ++box; //First add the box to 101, and then assign it to age

//= box ++; //First assign box to age, age=100, and then accumulate

//age = --box //First reduce box to 99, Then assign the value to age

//= box -- //First assign the box value to age age=100, and then subtract

+ -Operator

var box=100;

+box; //Positive number

-box //Negative number

The plus sign (+) has an automatic transformation function

As shown in the following code

Arithmetic operator

Add(+)

Minus(-)

Multiply(*)

Division(/)

remainder (%)

Assignment operator

Assignment operator Nested use of operators: the following case

Comparison operator

Ternary operator

Syntax: Expression 1 ? Expression 2: Expression 3

Example:

Note: If expression 1 is true, the output result is expression 2, otherwise it is expression 3; For example, in the above case x=5;, judge whether expression 1 is true. If true, output the value of

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&&(The conditions must be met at the same time to be true)

x=2;y=6;

x&&y>6 ;

At this time, x and y only have One item satisfies greater than 6, so the result is false;

||(As long as one of the conditions is met, it is true)

x=2;y=6;

x||y>6 ;

At this time, one of x and y satisfies the condition, so the result is true;

!(take The logic is worth the opposite, if it is true, take false, if false, take true)

x=5;y=8;

!(x>y);

First, judge whether x is greater than y. If it is not greater, it is false. If it is not false, it is true, so the result is true

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