JavaScript
provides eval function, which takes a string and evaluates the expression.
Syntax
eval(string)
What Can I
do using eval?
a. You can evaluate an expression.
Ex:
eval("2+5*7");
b. You can define a variable.
Ex: eval("var x = 10");
c. You can define a function.
Ex:
eval("function inc(x) {return x+1}");
In
addition to these, it replaces the variables with values while evaluating
expressions.
Ex:
var a=10,
b=20;
eval("a+b")
evaluates to 10+20 = 30.
eval.html
<!DOCTYPE html> <html> <head> <title>eval Example</title> </head> <body> <script> var a = 10; var b = 20; eval("var c=30;"); // Define a variable var sum = eval("a+b"); // Evaluate an Expression var expression = eval("2+5*7"); // Evaluate an Expression eval("function inc(x){return x+1;}"); // Define a function document.write("c = " + c + "<br />"); document.write("sum = " + sum + "<br />"); document.write("expression = " + expression + "<br />"); document.write("inc(10) = " + inc(10) + "<br />"); </script> </body> </html>
Load above
page in browser, you can able to see following text.
c = 30
sum = 30
expression
= 37
inc(10) =
11
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