繰り返し

 
■概要
 
JavaScriptの繰り返しも、C, javaなどの言語と似てます。
見てみましょう。
 
■while文

var num = 0;
while (true) {
　document.write(num);
　if (num++ > 5) break;
}

 
■for文

var arr = [‘red’, ‘blue’, ‘green’, ‘yellow’, ‘black’];
for (var i = 0; i < 5; i++) { 　document.write( arr[i] ); }

 
■for in文

var colors = [‘red’, ‘blue’, ‘green’, ‘yellow’, ‘black’];
var user = {
　’name’: ‘tester’,
　’birth’: 2000,
　’sex’: ‘m’
}

document.write(‘<h3>colors</h3>’);

for (var i in colors)
　document.write( i + ‘: ‘ + colors[i] + ‘<br>’ );

document.write(‘<h3>user</h3>’);

for (var i in user)
　document.write( i + ‘: ‘ + user[i] + ‘<br>’ );

出力結果

colors

0:red
1:blue
2:green
3:yellow
4:black

user

name:tester
birth:2000
sex:m