规则名 | 规则类型 | 深入了解 |
---|---|---|
no-param-reassign |
suggestion |
Assignment to variables declared as function parameters can be misleading and lead to confusing behavior, as modifying function parameters will also mutate the arguments
object. Often, assignment to function parameters is unintended and indicative of a mistake or programmer error.
This rule can be also configured to fail when function parameters are modified. Side effects on parameters can cause counter-intuitive execution flow and make errors difficult to track down.
This rule aims to prevent unintended behavior caused by modification or reassignment of function parameters.
此规则的 错误 代码实例:
/*eslint no-param-reassign: "error"*/
function foo(bar) {
bar = 13;
}
function foo(bar) {
bar++;
}
function foo(bar) {
for (bar in baz) {}
}
function foo(bar) {
for (bar of baz) {}
}
此规则的 正确 代码实例:
::: correct
/*eslint no-param-reassign: "error"*/
function foo(bar) {
var baz = bar;
}
This rule takes one option, an object, with a boolean property "props"
, and arrays "ignorePropertyModificationsFor"
and "ignorePropertyModificationsForRegex"
. "props"
is false
by default. If "props"
is set to true
, this rule warns against the modification of parameter properties unless they're included in "ignorePropertyModificationsFor"
or "ignorePropertyModificationsForRegex"
, which is an empty array by default.
选项 default { "props": false }
的 正确 代码示例:
::: correct
/*eslint no-param-reassign: ["error", { "props": false }]*/
function foo(bar) {
bar.prop = "value";
}
function foo(bar) {
delete bar.aaa;
}
function foo(bar) {
bar.aaa++;
}
function foo(bar) {
for (bar.aaa in baz) {}
}
function foo(bar) {
for (bar.aaa of baz) {}
}
选项 { "props": true }
的 错误 代码示例:
/*eslint no-param-reassign: ["error", { "props": true }]*/
function foo(bar) {
bar.prop = "value";
}
function foo(bar) {
delete bar.aaa;
}
function foo(bar) {
bar.aaa++;
}
function foo(bar) {
for (bar.aaa in baz) {}
}
function foo(bar) {
for (bar.aaa of baz) {}
}
Examples of correct code for the { "props": true }
option with "ignorePropertyModificationsFor"
set:
::: correct
/*eslint no-param-reassign: ["error", { "props": true, "ignorePropertyModificationsFor": ["bar"] }]*/
function foo(bar) {
bar.prop = "value";
}
function foo(bar) {
delete bar.aaa;
}
function foo(bar) {
bar.aaa++;
}
function foo(bar) {
for (bar.aaa in baz) {}
}
function foo(bar) {
for (bar.aaa of baz) {}
}
Examples of correct code for the { "props": true }
option with "ignorePropertyModificationsForRegex"
set:
::: correct
/*eslint no-param-reassign: ["error", { "props": true, "ignorePropertyModificationsForRegex": ["^bar"] }]*/
function foo(barVar) {
barVar.prop = "value";
}
function foo(barrito) {
delete barrito.aaa;
}
function foo(bar_) {
bar_.aaa++;
}
function foo(barBaz) {
for (barBaz.aaa in baz) {}
}
function foo(barBaz) {
for (barBaz.aaa of baz) {}
}
If you want to allow assignment to function parameters, then you can safely disable this rule.