For:
define：
The for statement can customize how many times you want to execute code
Grammar：
for (condition 1; condition 2; condition 3)
{
code
}
Condition explain:
| condition | describe |
| 1 | prestart before beginning. |
| 2 | loop condition. |
| 3 | Execute after the loop has been executed. |
Example：
for (var i=0; i<5; i++) { x=x + "The number is " + i + "<br>"; }
The code 's output:
The number is 0
The number is 1
The number is 2
The number is 3
The number is 4
For/in:
define：
The for/in statement is used to loop through the object properties。
Grammar：
for (var in object) {
code
}
parameter values:
| parameter | describe |
|---|---|
| var |
Must.variable can be an array element or an attribute of an object. (指定的变量可以是数组元素，也可以是对象的属性。) |
| object |
Must.Object that specifies the iteration. (指定迭代的的对象。) |
Example：
1 var string = {lesson:"web", verb:"is", describe:"fun"}; 2 3 var text = ""; 4 var x; 5 for (x in string) { 6 7 text += string[x]+" "; 8 }
The code 's output:
web is fun
For/of:
define：
The for/of statements creates a loop iterating over iterable objects.
Grammar：
for (variable of iterable) {
statement
}
parameter values:
| parameter | describe |
|---|---|
| variable |
On each iteration a value of a different property is assigned to variable. (在每次迭代中，将不同属性的值分配给变量。) |
| object |
Object whose iterable properties are iterated. (被迭代枚举其属性的对象。) |
Example：
1 let iterable = [10, 20, 30]; 2 3 for (let value of iterable) { 4 value += 1; 5 console.log(value); 6 }
The code 's output:
11 21 31
Related Pages:
JavaScript for : http://www.runoob.com/js/js-loop-for.html
JavaScript for/in : http://www.runoob.com/jsref/jsref-forin.html
MDN - for...of : https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Statements/for...of
Javascript statement : http://www.runoob.com/jsref/jsref-statements.html