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introduce a warning with misusage binding in dev mode #4084

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introduce a warning with misusage binding in dev mode #4084

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e709e92
introduce an warning if there is a misusage of v-bind
defcc Nov 1, 2016
6da8ff9
add flow type
defcc Nov 1, 2016
78e2dad
change to rawName for consistency
defcc Nov 1, 2016
5493878
add test case
defcc Nov 1, 2016
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31 changes: 31 additions & 0 deletions src/compiler/parser/index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -366,6 +366,9 @@ function processAttrs (el) {
name = name.replace(modifierRE, '')
}
if (bindRE.test(name)) { // v-bind
if (process.env.NODE_ENV !== 'production') {
checkVBindingVal(rawName, value)
}
name = name.replace(bindRE, '')
if (modifiers && modifiers.prop) {
isProp = true
Expand All @@ -382,6 +385,9 @@ function processAttrs (el) {
addHandler(el, name, value, modifiers)
} else { // normal directives
name = name.replace(dirRE, '')
if (process.env.NODE_ENV !== 'production' && name === 'bind') {
checkVBindingVal(rawName, value)
}
// parse arg
const argMatch = name.match(argRE)
if (argMatch && (arg = argMatch[1])) {
Expand Down Expand Up @@ -410,6 +416,31 @@ function processAttrs (el) {
}
}

function checkVBindingVal (name: string, value: string): void {
let func

// there may be template error, leave it to the compiler detectErrors
try {
func = new Function(`(${value})`)
} catch (ex) {
return
}

try {
func()
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While being a savvy technique, this is also very very dangerous. It will introduce code execution, especially if expression is passed from user input or database.

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@defcc defcc Nov 2, 2016 •
edited
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En, this is just a check in dev mode. If the expression passed down is plain js code like 'alert(1)', it'll be warned.

<component :val="alert(1)"></component>

} catch (ex) {
return
}
// if v-bind value is literal, the evaluation causes no error, we should introduce a warning.
warn(
`${name}="${value}": ` +
`You are using v-bind with literal. ` +
`To get better performance, ` +
`if is an object/array literal, save the literal in data/computed property, use like <component :ids="list"> instead of <component :ids="[1,2,3]">; ` +
`otherwise use like <component ids="1"> instead of <component :ids="1">`
)
}

function checkInFor (el: ASTElement): boolean {
let parent = el
while (parent) {
Expand Down
5 changes: 5 additions & 0 deletions test/unit/modules/compiler/parser.spec.js
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Expand Up @@ -280,6 +280,11 @@ describe('parser', () => {
expect(ast.props[0].value).toBe('msg')
})

it('warn v-bind with literal', () => {
parse('<my-component :value="{}"></my-component>', baseOptions)
expect('You are using v-bind with literal').toHaveBeenWarned()
})

it('attribute with v-on', () => {
const ast = parse('<input type="text" name="field1" :value="msg" @input="onInput">', baseOptions)
expect(ast.events.input.value).toBe('onInput')
Expand Down