What are the differences between php and js? _PHP Tutorial

1. Differences in type conversion

in javascript

Empty objects and empty arrays are converted to boolean values ​​of true;

But in php

Empty object and empty array are converted to boolean value as false;

(only in php4 the boolean value of empty objects is false)

Negative values ​​including non-0 are converted to true;

2, Differences in actual parameters

There is no limit to the number of formal parameters and actual parameters in js. The number of formal parameters can be greater or less than the actual parameters

In PHP, if the actual parameters are greater than the formal parameters, no error will be reported, but when the number of actual parameters is less than the number of formal parameters (and an error will be reported when the unspecified formal parameters are undefined)

<span function</span><span  mao(val1,val2,val3){
}
mao(aa,bb);</span>

But when val3 initializes a value, no error is reported

<span function</span> mao(val1,val2,val3="123"<span ){
}
mao(aa,bb);</span>

The essential reason is that PHP does not have a prototype connection and there is no variable object during execution.

3. Differences in data types

There is an undefined type in js, but there is no such type in php,

So when a variable is not assigned any value, the type is undefined in js (an error will be reported when using undeclared variables), but it is Null type in php;

And there is only number type in js, but there is no such type in php, it is replaced by int float type;

4. String concatenation

Use plus sign + +=

in js

Use dots in php ..=

5. The difference between control statements

else if and elseif are both supported in php, js only supports the former

6. Capitalization problem

js is strictly case sensitive

Custom function names in php are not case-sensitive. When naming a function, you cannot use declared functions or PHP's built-in function names.

7. Scope of variables

Variables declared by PHP outside the function scope are global variables. Since a function can be regarded as a separate
program fragment, local variables will override the visibility of global variables. Therefore, there is no
method to directly call and use global variables in the function. When you want to use a global variable in a function, you must use the global keyword to define the target variable and use
to tell the function body that this variable is global.

js can be called directly due to the prototype connection

8. Static variables

PHP supports declaring function variables as static

js does not have static variables but you can define function attributes to pretend to be static variables

http://www.bkjia.com/PHPjc/440222.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/440222.htmlTechArticle1. The difference in type conversion is that in javascript, empty objects and empty arrays are converted to boolean values ​​of true; but in php, they are empty. The empty array of objects is converted to a boolean value of false; (only in php4 the empty array of objects...