ESLintDisallow Shadowing of Variables Inside of catch (no-catch-shadow)
In IE 8 and earlier, the catch clause parameter can overwrite the value of a variable in the outer scope, if that variable has the same name as the catch clause parameter.
var err = "x";
try {
throw "problem";
} catch (err) {
}
console.log(err) // err is 'problem', not 'x'
Rule Details
This rule is aimed at preventing unexpected behavior in your program that may arise from a bug in IE 8 and earlier, in which the catch clause parameter can leak into outer scopes. This rule will warn whenever it encounters a catch clause parameter that has the same name as a variable in an outer scope.
Examples of incorrect code for this rule:
/*eslint no-catch-shadow: "error"*/
var err = "x";
try {
throw "problem";
} catch (err) {
}
function err() {
// ...
};
try {
throw "problem";
} catch (err) {
}
Examples of correct code for this rule:
/*eslint no-catch-shadow: "error"*/
var err = "x";
try {
throw "problem";
} catch (e) {
}
function err() {
// ...
};
try {
throw "problem";
} catch (e) {
}
When Not To Use It
If you do not need to support IE 8 and earlier, you should turn this rule off.
Version
This rule was introduced in ESLint 0.0.9.