单击按钮时如何更改此输入的值？

Question

I'm trying to write a program which has several textboxes and 1 button. When the user clicks the button the value for the textboxes changes to how are you .

I'm not sure how to refer to the value i for the expression document.getElementById('text'+i).value= 'how are you'

 <input name="text1" type="text" id="text1" value="textbox 1"                 
 onFocus="this.style.background ='yellow'" onBlur="this.style.background='white'">
 <input name="text2" type="text" id="text2" value="textbox 2"                             
 onFocus="this.style.background = 'yellow'" onBlur="this.style.background='white'">

function popup() {
    for( int i; i <2, i++) {      
      document.getElementById('text'+i).value= 'how are you'      
    }
}  

<input type="button" value="Click Me!" onclick="popup()"><br />

I have changed the for loop part, but its still not quite working:

function popup() {
    for( var i = 1, i <= 2, i++) {
      document.getElementById('text'+i).value= 'how are you'
    }
}

Would the program work with a foreach loop like in C++ ? First it will count the number of textboxes you have and then create a list which goes from 1 to the total number of textboxe, then write a for loop to count the textboxes.

Answer 1

for(var i = 1; i <=2; i++) {
    document.getElementById('text'+i).value= 'how are you'      
}

---

Clarifications:

• You need to init i to be 1
• you need to change the break condition to i<=2

JavaScript is dynamic typing language, so there are no types in the variable declarations.

The errors you had by @esailija:

• i not initialized to number.
• , instead of ;
• int i instead of var i
• off by one error.

Answer 2

Use the word var to declare variables in JS. And don't forget your semi-colons.

function popup() 
{  
  for(var i=1; i <= 2; i++) {     
    document.getElementById('text'+i).value = 'how are you';        
  }  
} 

Answer 3

Just for simplicity, I'll point out that a for loop that has only two iterations and one line of code inside the loop is kind of a waste of typing. You could also just do this:

var str = 'how are you';
document.getElementById('text1').value = str;   
document.getElementById('text2').value = str;   

Answer 4

• var is used to declare variables in javascript
• variable should be initialized in for-loop
• for-loop condition should be correct to ensure it loops the right amount of times. < 2 would make it stop on 1.

As I understand you, you want the i variable to show in your text as well. Just add + i at the end of the string. Otherwise, just remove that part.

This will loop through "text1" and "text2"

for( var i=1; i <= 2; i++) {
  document.getElementById('text'+i).value = 'how are you' + i;
}