Javascript: Difference between revisions

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(Created page with "== Reference == * [https://www.w3schools.com/jsref/ JavaScript and HTML DOM reference on w3schools.com] == Syntax == JS type: <source lang=javascript> // Strings var carname...")
 
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// void
// void
void(0); // evaluate expressions and returns undefined
void(0); // evaluate expressions and returns undefined
</source>

JS statements:
<source lang=javascript>
// while
while (i < 5) {
// ...
}
</source>
</source>

Revision as of 01:37, 26 December 2017

Reference

Syntax

JS type:

// Strings
var carname = "Volvo XC60";

// Numbers
var x = 3.14;
var y = 34;

JS operators:

// Arithmetic operators
x = y + 2;
x = y - 2;
x = y * 2;
x = y / 2;
x = y % 2;       // Modulus (division remainder)
x = ++y;         // Pre-increment
x = y++;         // Post-increment
x = --y;         // Pre-decrement
x = y--;         // Post-decrement

// Assignment operators
x = y;
x += y;
x -= y;
x *= y;
x /= y;
x %= y;

// String operators
text3 = text1 + text2;     // Concatenation
text1 += text2;

// Comparison operators
x == 8;    // equal to
x === 5;   // equal value and equal type
x != 8     // not equal
x !== 5    // not equal value or not equal type
x > 5;
x < 5;
x >= 5;
x <= 5;

// Ternary operator
voteable = (age < 18) ? "Too young" : "Old enough";

// Logical operators
x && y;     // logical and
x || y;     // logical or
!x;         // not

// Bitwise operators
x = 5 & 1;  // bitwise and
x = 5 | 1;  // bitwise or
x = ~5;     // bitwise not
x = 5 ^ 1;  // bitwise xor
x = 5 << 1; // bitwise left shift
x = 5 >> 1; // bitwise right shift

// typeof
typeof "John";            // returns string

// delete
var person = {firstName:"John", lastName:"Doe", age:50, eyeColor:"blue"};
delete person.age;        // or delete person["age"] -- delete property from an object

// in
var cars = ["Saab", "Volvo", "BMW"];
"length" in cars          // true if property is in the specified object
"firstname" in person

// instanceof
cars instanceof Array;    // true if object is instance of specified class

// void
void(0);                  // evaluate expressions and returns undefined

JS statements:

// while
while (i < 5) {
    // ...
}